She did this, she did that, what a greedy, conniving, heartless so-and-so. You’re friends nod and agree, they pile on, they say they never liked her, they go through all your shared stories about what a bitch that bitching bitch is. This kind of talk is incredibly validating, it gives you a sugar rush of strength, it can carry you through some dark nights. Maybe this is good for you on some level ... But if you have kids?
Don’t do it. If you want to be a successful parent to your kids, you cannot let them feel your bad feelings about their other parent. No matter what she’s done, no matter who she’s with, no matter how you feel - you cannot pass that burden onto your kids.
And what happens when your friends support your bitch session is that your negative feelings harden. You get used to saying nasty things about your ex and receiving positive reinforcement for it. You have a higher chance of letting a negative statement slip out in front of your kids, and even if that doesn’t happen, the very glow of that radioactive bitch session will seep through your skin and shine its evil rays on your children.
If your friends truly want want to be friends of your family rather than an inadvertent enemy, they must support you in this. No negative talk, no affirmation of nasty thoughts, no reinforcement of your counterproductive tendencies. Don’t bitch to your friends about her, and if you do, tell them as a friend what you need is correction, not corroboration.
In the best possible case - not all of us can manage this - you could get it right from the start. Even if this can’t be you, think about how to get in this same state where your friends support your family by refusing to be your ex’s enemy.