I think it depends on what you want to do and how it affects you.

First and foremost - do you WANT to be involved? Does SD WANT you to be involved? No is a perfectly acceptable answer. You aren't her mother, and she isn't your daughter. Neither of you have an obligation to be familial.

If one or neither of you want to be involved, then I see no reason why you shouldn't go do something else for the day. That's not being passive aggressive - that's just how life works. When you don't have plans and you want to do something, you go do something.

Now, if you're planning to do this to snub your DH and his daughter, that's not a healthy approach. If you're doing it because you don't want to be involved or recognize your presence isn't wanted, then that's perfectly acceptable. Again, no reason to twiddle your thumbs at home.

As for the jealousy of the flirting XW, think about how it makes HER look to be flirting with her MARRIED XH at her daughter's family event in a MENTAL HEALTH FACILITY. Anyone who isn't blind is going to look at that and understand not only why they are divorced, but why DD is there to begin with. Basically, it says a lot more (negatively) about her than it does you or your DH.

Don't feel guilty for any of this. Disengagement is perfectlt acceptable, and sometimes the healthiest thing we can do. You're good.

I guess it just depends on what it is you really want to do. Do you want to accompany your husband or not? Had you outright been invited, would you go? Is it possible your husband was waiting for your reaction on whether to ask you to go or not? And since you didn't ask any questions or give much of a response, he assumes you don't want to go? Really, some communication is necessary.

Him being in the same place as BM is not necessarily playing "happy family". But if you are concerned about that, tell him that you would like to accompany him.

Personally, I would have the conversation with your husband. If you want to go with him, tell him. If you want to make other plans for yourself for that day, tell him.

I woud be relieved to not be invited.  You didn't say if this was part of her job or part of her counceling exactly but if its a part of her counceling, then maybe she didn't want you there.  The councelor might also need to see the dynamics at work and the BM show.  I'd be sure to kiss DH with a memorable one, wink about things to do when he gets home and send him on his way with YOU and naked time on his mind.  You go have a great day taking care of yourself.  Be prepared for him to be in a worse mood then better mood so you aren't to dissappointed in him.  Hopefully the thought of you in the back of his mind will help him to cut out early and come home to you.  

On the one hand, you don't want to go where you are not welcome nor have been invited.  On the other, this SD has never excluded you before so I can understand why it is troublesome.  Especially when you add a pot-stirring flirtatious BM to the mix.  You assume that the other skids will be there but is it possible it will just be BM and your DH in attendance?  

Is it also possible that you were not necessarily excluded?  Maybe your DH just worded it as "I've been invited..." and was testing you out to see if you had any interest in going.  In a way, I can see that your DH may be between a rock and a hard place.  If he says you are invited, too, then he risks your response.  Either you can decline (and possibly upset SD) or if you accept then he may feel you are being pressured to go even if you don't want to, especially with his ex being there.  Like many men, he communicates in a way that he THINKS prevents conflict.  

Is your DH just going to attend the event at the counseling center?   If that's all it is, it's understandable that DH attends.  However, if anyone (BM perchance?) wants to plan additional activities such as dinner, etc. so they can all play happy family, then he should decline and get his butt home to you.    

Going to an event like this is not necessarily a big deal but only you can understand what undercurrents may be at play beyond the superficial calm waters of this issue.

It's all dependent on circumstances.  Is the adult skid a worthless POS or is this maybe a child who needs some extra help?

It is possible that SD thinks that you are invited and DH worded it badly? There is nothing to lose by asking him the details of the invitation.  If it was just him, you have your answer. If she said can you (plural) come, that is different.

If this were a specifically invited counseling session (birth parents), I could understand your not being involved. But, a family and friends event is completely different. Your not going is a deliberate exclusion. And deliberate exclusions hurt.

I'd try to clarify the exact invitation with DH as suggested above. If the invitation is as DH presented, then DH needs a wake up call. Accepting a family and friends event invitation that excludes your wife is not acceptable. 

It sounds like you are actually uncertain of the invitation.  Rather than guess, I think it would be smart to simply ask your DH and, if he does not know, have him ask his daughter.  The basic issue of whether you are invited or not does not need to be a question.  If you try to guess and guess wrong then that could cause unnecessary drama.  Find out for sure. 

and don't have any further concerns then do indeed plan to do your own thing for the day.  

However, my only caution is this - if your DH is "uncomfortable" talking about all this, then in my mind there may be more to it.  The fact he said "possibly" the siblings might mean he knows it's only just going to be him and BM in attendance and he does not want to admit this.  

IMO, he should be honest and upfront with you when it comes to any of his dealings with BM.  He should say, "SD only wanted her parents at this event so BM and I will be there to support her.  After the event is over, I have no intention of being around BM any longer than necessary and will be leaving to come home.   I won't be going to any lunches, dinners, etc. that involve her as I don't care to be around her.  I will politely decline and say that I have plans with you (my wife) and will be heading home."

So why can't he say that??

I would go.  Go for a make-over and spa day, hit your favorite clothing boutique and be radiant when you walk in on your DH's arm.

Cockroaches scurry for the dark corner when a light is thrown on.  Be the light. The roaches will scurry.  Be supportive, but be present.  Do not let these people marginalize  you or your marriage.

consult with the therapist, and then at some point in the future you might be brought in, once they complete the intake process? Just curious to know if that might be an option.

Idvilen, you are right. Nobody wants to be the "mom" to other people's kids, however, common decency with demonstrated respect would be nice. You would think you wouldn't have to have conversations about that, especially with so-called "grown" people.

The other thing that's unrealistic is these articles that say, "SK's were present LONG befoe you arrived on the scene, so you need to step aside and get over it. Allow the family time together. You need to realize you are the "new kid on the block". Don't rock the boat." etc. Really? What about what The Bible says about marriage? It doesn't say "Only FIRST marriages count as being a covenant." ANd it doesn't make reference to secondary marriages being inferior to the first, It says "MARRIAGE".

Good for you.  I wouldn't even ask  just enjoy your time.  Don't ask, he will talk about it if he wants you to know.  Don't talk about it all, thus enhances you feelings.  Have a nice time to your own privacy.

I relate to all your feelings and understand.  I can assure you not knowing and letting it go is better for you.  I go thru this often, but it is getting much easier to let it go.  I even forget the mess within a few minutes after it is over now.

When does this all happen?  I'm dying to know how this all plays out so please update us on this day.