Total loss

I feel completely worn out in the subject. My boyfriend of many years who we have a child with seems to be bending over backwards for his other baby mama (who takes advantage of it) they where split long before me and him got together. Over the last year or so he has been so “buddy buddy” on social media and texting it drives me nuts! It is to the point it has nothing to even do with the other child (she’s married to) I’ve expressed my feelings about the constant messages and social media comments I’m at a total loss as it results into a fight every time!! And I’m at fault for “making shit up” what do I do.. it’s ruining us and he doesn’t seem to get it...