DH and I called out his mother and step father in a major way,  in Spring of 2018, and as of then have been estranged from them.   He has recently begun exchanging the occasional email with her, but I doubt I will ever speak to her again.   If you do call them out, you need to be prepared that this might happen. 

I think you should at least TRY to talk to them about how you feel, but if it's an endless cycle of you doing that and them being defensive and dismissive, then you have to decide if it's time for you to let go.

When deciding whether to say something, I think about that saying "Is it true, is it kind, is it necessary".

Now, we can argue whether it's necessary to "be kind" to someone that may be intentionally hurting us... but to an extent, when dealing with people that are close to us, there may be some level of giving someone the benefit of the doubt.  If my DH says something that can be taken two ways... "hurtful and not hurtful".. why would I automatically assume that someone that loves me is trying to hurt me... so if the inlaws aren't particularly toxic.. maybe their intent hasn't been totally ill.

Anyway, so, then on to the other two points.

First, is it true, Is what they are saying untrue? Is what you would need to tell them true.  If they have a misconception about a reality.. have facts wrong.. then you definitely can proceed to the third point

Is it necessary.  What is the possible outcome?  Is saying something going to fix or improve the situation?  Is it necessary for them to understand your POV so that they don't repeat their mistakes in the future?

I mean, sometimes we can disagree with someone's POV.. and we know they aren't going to change their belief, so we could talk till we are blue in the face and they will never see our viewpoint. In these cases.. sometimes just ignoring their advice.. is all we need to do.  "Yeah, thanks for the input, I will look into that" or whatever.  

It all depends on the closeness of the person saying something.  LIke your inlaws.. as long as you are in the relationship, you will have to deal with them.. so how worth it is it to start some big conflict with them.. I am actually in a situation currently with my MIL and to a certain extent... it is an uncomfortable situation.. BUT.. my DH supports my position.. it's also his position.. so we kind of are where we are on it.  

But, if you think that your inlaws are somewhat clueless and a kindly worded response could prevent them from saying the things that you find hurtful.. then I would speak up.  If you think they are boorish and are intentionally out to get you, you have nothing to gain by confronting them.. might as well just disengage to the extent you can.

BTW... in your particular case, you are estranged from these people.. so ghosting is entirely appropriate.  Why on earth break that distancing by trying to call them out on some poor behavior.

Per your last post, you are upset they didn't give you condolences but sent you a card for your birthday.  I don't know why they did that? maybe they have cards on auto send? who knows.. but obviously you have reasons to not speak to them.. so why does it matter what people that don't matter to you do?  You don't have a relationship with them.. just discard the birthday card and move on with your life.

If you are estranged there is no need to contact them 

My SIL has an evil SM: a beeyotch whose been a high school mean girl for 7 decades. Because my parents raised me to be respectful of my elders, I bit my tongue for damn near 4 decades. Until Thanksgiving 2 years ago...

She was already at 2 strikes when...

SM: Aniki, have you lost weight?
Me: Yes, a little.
SM: Well, good. You need to. You're pretty damn fat.

What.The.F*ck. 
What kind of person says that? Yes, I'm overweight, but I'm not a freaking beached whale. And Stepmonster, who is built like a stack of tires, has NO room to talk. That was the last bloody straw and my temper - usually a unicorn - let loose.

Me: I feel sorry for you, Stepmonster.
SM: WHAT???
Me: I feel sorry for you.
SM: SORRY for me - why??
Me: For whatever happened in your life to make you so negative and hateful that you find it necessary to talk down to people and treat them like shit. You must feel terribly ugly on the inside to try and make others feel badly about themselves. I know you're old, but it's not too late to go to therapy, get help, and strive to become a decent person.

ETA: I'd forgotten you're estranged from your out-laws. Ghost away! However, if for some reason you decide to associate with them, find your voice!

My general framework:

If I don't have to interact with them, ghost them.

If I do have to interact with them again, try to work it out as a first step. Then call them out if talking it out won't work. Then ghost if that didn't work, either.