I've been active here today
. My DH and I have been together for 3yrs. He has other children we have a DD together. The other BM's (Yes I have TWO to deal with) were both civil at first. One much more than the other. The better my DH and I got along the meaner they got. The closer I tried to get to the children the more they pulled the kids away. To the point that he didn't want the conflict and stopped most contact. One of them even threatened to beat me up. I haven't encountered this much drama since jr high. We finally tied the knot last month we haven't heard from either mother or any of the children since they found out about the wedding. I think a big thing that we all need to accept is that no matter how much two people don't want to be together and no matter what they say about how unhappy they were together, at one point they were happy, and they created beautiful children and when the person you were with finds someone new and worse it looks like it could be better than what you had a lot of emotions come up and often turn hostile. Time will heal most of this along with patience and gentle pursuasion.
I agree with the PP who said keep it positive so the kids don't have to feel like "who's right". No matter what horrible things the older two kids moms say about me, I ALWAYS get a warm welcome from the kids. Honestly I tried being nice to their mother. If she has enough friends good for her, I really only care what the kids think anyway.