Dash Riprock
Master Don Juan
Bury her.I know.....
I would start documenting conversations with her over text and email and if at some point you put together enough "evidence" that she's not providing a safe environment for your child, THEN you could legally take action if you want full custody. Get her to talk about her boyfriends, FWBs, going out, drinking, etc., and document all of it. Then, hit her with the attorney bomb when she least suspects it. In other words, be a f*ucking pr*ick about it and take no prisoners.
Don't be so sure the "serious boyfriend" won't work out. PLENTY of beta male providers out there that will pay $$$$ for her and the kid just for your ex to date and fu*ck him.
Good luck.