BM left my SO when their son was 2. He also had a son from a previous rship, and that child was 3 when BM and my SO divorced. From what I understand, BM never had much interest in his other son during their short 2 year marriage. And she left my bf for a man who has no job.
BM and SO are getting along beautifully now (4 years later), which I hate. They talk/text a few times/day and they are fb friends. SO has their son all the time because she is in Grad school and doesn't have time. He doesn't pay child support b/c they have 50/50 custody. SO enjoys having their son over more than 50/50, because SO doesn't like her boyfriend and does not want the boy around him much.
Anyway, here is what annoys me: She left him for another guy. But now that they are friends, she is acting like they are bff. And, on FB, she is now making comments on old photos that have both of his sons in it. She said "Look at how small the boys were", or, "The boys are were soooo cute back then". I'm annoyed because "the boys" imply, IMO, her kids. No. His older son is not her kid. I don't know why she is making comments about him. She wasn't interested in him while they were married, so why is she all goo goo gaga over him now? And she is always saying stupid shit like "I miss my BOY, can't wait to see my BOY" on her wall. And bf seems to think this makes her a good mom. IMO, she should miss her boy... because she never has time for him because she is a shitty mom.