Then there is plenty of work ahead.  Otherwise, Divorce and get out now for your sanity.

That said; if you intend to stay, then get both of you to counseling asap and set boundaries with her.  First of all attacked you?   Physically?  In that case I would have either put him in a cast or in Jail.  That is assault and yes you should file a police report immediately.

Also, I have to ask Why is she spending time with kids and the ex outside of a family counseling type situation?  This sounds beyond a little suspicious to me.

From experience it is as simple as this and either she works with you or I would leave asap.

1.) Your marriage is at the center and provides stability for the kids

2.) Your marriage comes first.  The kids may need a relationship with the Ex but she does not

3.) If ex has been violent do not be shy.  Call the police, get a protective order.  Do not play

This is a toxic situation and much work is needed by both you and DW otherwise, this marriage will not succeed. 

What is she doing with her ex - why is she spending time with him? How much time?

This is one of the many issues with being a childless step-parent or only having "ours" children.  The true one-sidedness of it all.  You get it coming at you several different ways.  First of all, even tho. you have never been married before, you not only get the title step-parent, but you get all of the lovely negative stereotypes that come with that term, AND your marriage or releationship will still be seen as an "inferrior" one simply because your partner has had kids with someone else.  

Heck, I've even seen several comments about how step-parents should expect to have a lesser marriage because it is their 2nd or 3rd, etc.  Well, hello people!  Not every step-parent has been married before or has children themselves.  I take all of this as sheer ignorance on the part of mainly non-steps, but it does let you know how many people out there are so out of it on the realities of step-parenting.  Step-parents come in all shapes and sizes, just like any other minority.

So, here it is your first marriage, and you have the Evil step-parent label and sloppy-seconds label just because you married or got involved with someone else with children.  Then, to top it off, step-parents are ever told they have to suck it up and take it and "kids first," etc.  Well, what if your partner has kids from a prior relationship and you don't?  Where does that put you?  Personally, no one here really believes that "kids first" mantra, anyway, because bioparents don't even put their kids first.  They'll scream at each other in front of the kids, have affairs, etc., but suddenly after the divorce, it becomes "kids first," and this allows the bio-parents to do whatever they darn well please, while their new SO or spouse is expected to sit off to the side and not interfer when BM and bio-dad and the kids want to play together.

You 100% bet it is a lopsided relationship or marriage if you have no kids outside the marriage, but your partner does.  You get to sit there and feel like a 3rd wheel, which is actually putting it nicely.  What you really are, is some other family's lackey or indentured servant, maybe finally earning your freedom when they kids age out.  Maybe.  For added "fun," you get to help support someone else's children, while no one is helping you along, other than maybe to bellyache when you act too much like bio-dad.  Kids always = money, time, committment.  You are paying this all out on your end, and not much is coming back your way.  You can wait years waiting for any kind of pay-off, and it may never come.

The reality is, no marriage will survive if it is not given the priority, and that doesn't mean screwing the kids (that's another thing I absolutely hate, when people act like someone has to get screwed, and if anyone is, well, of course it is going to be the outsider step-parent).  Another poster here well-said that marriage should be the #1 priority and the kids are the #1 responsibility.  That is the way it should be.

As this woman's spouse or long-term SO, if you don't want her hanging out with her ex-, then she should respect that and not do so.  She can hang out with her kids all she wants, but when she is hanging out with the ex- without your OK, she is putting him first and not you.  It has nothing to do with the family.  Getting the divorce is a choice the parents made and not you.  That is their burden to carry and not yours.  Divorce is not supposed to = happily ever after.  Marriage is supposed to.

Time to have a "coming to Jesus" meeting with your partner, and she'll be.atch about it, more than likely.  Accuse you of being immaure and not getting it because you haven't been in her shoes.  But, you know what?  All of that is irrelevant, because SHE is your partner, and you are supposed to be HER partner.  It is possible to go on to a new relationship/ marriage, be true that that marriage, and yet be a decent parent to your child, and not hang out with your ex-; unless, at least, your current partner is along and you make sure everyone sees you as being co-joined with your new partner and not your ex-.  

All of this is done because not many really understand that when you ask a partner with no children from a previous relationship to suck it up and take it for your ex- and children, that you are already setting up that relationship for absolute failure.  No one wants to be anyone's sloppy seconds, especially when it is their firsts.  If you're supposed to sit back and watch while your partner and her ex- and kids all hang out, she is thinking that she is so great she can have her cake and eat it too, while you are left with only whatever crumbs she chooses to give you.  That is not a marriage, and it is no a relationship.  It is hell.  It is step-hell.  (And, to me, an even bigger hell is her hanging out with an ex- that threatened you!  How is that making you a priority?)

The kid is 24yo??? Could  she and her ex have "rekindled" their relationship? 

The kid is 24, that completely changes things. He is an adult, he can spend time with his parents without the other parent being there. It is not like it is a school event or something like that. She is choosing to spend time with an adult in the prescens of another adult who physically attacked you. That is not right.

Listen to your gut. If you think they might be involved you will have to decide how you want to handle it.

In any case, you need a real heart-to-heart to get to the bottom of things.

Oh my lordy. 24. When my kid was 24, I talked with or saw my ex when our grown child had some serious health issues, graduated from college, and got married. That's it. (And each time I clearly remembered why I divorced him.) And I have had a great relationship with my adult child throughout.

To me, your DW's behavior just isn't normal. You're not asking her to abandon her kid, but you are asking her to prioritize your marriage.