Hi all need some advice so my ex and I had a horrible relationship anyway that ended in September last year , 2weeks later he was seeing someone new she's 12 years younger no kids has made it clear shes no interest in his kids but regardless he was still seeing our son , now he has completely changed , it was my sons birthday 1st of March he completely missed it to take his new gf on holiday didn't even get our son a present, iv told him he needs set days n he refuses to last night I told him about our son getting additional help and I just got abuse saying as well if I take him for his next lot of jabs he will sue me obviously turned into abit of an argument via message and after mentioning about missing his sons birthday putting her first he said he doesn't care what I think she's his gf iv heard they both do drugs aswell now so I'm not happy about that and apparently i cant do anything unless i have proof I'm at my wits end tried being fair and gave him enough chances but I just get crap back or empty threats !