betrayal

so I got divorced he sends support every month ,but he doesn't text,call,email , message the 800 million ways you can now these days, nothing I beg and beg for him to talk to his daughter ( we divorced when she was 1 hes a nasty piece of work in person and a shitty husband lol) so I complained casually to my mom about not getting ahold of him for her 6th birthday it's all she wanted was a call from him. my mother goes on well I'll talk to him later about calling an hour later I get the first message I've gotten from him in 4 years!!!!

I'm so beyond pissed I'm glad that a week after that text my daughter finnally got to speak with him!! am I crazy I feel betrayed why is my mother talking to my ex husband?? am I wrong for feeling completely betrayed by this ,he didnt even have the respect to tell me in advance he was reducing the support by $300, the same man who called me fat at 120 pounds after having his daughter, this is the very man that destroyed me but my mother loved him because he makes really good money ( no amount I ever saw it was all his I had to help pay rent,food ect.) and yet here they are talking to each other regularly ? but can't call the 6 year old child? neither of them can even remember her birthday idk what to do