Feel like crying! Help me 😭

Ok so me and my september babes father split up at xmas, it wasn’t working i was doing it all myself etc. Every saturday (most of the time) he has taken her, even before the split i was goin back to work on a weekend shift, sat/sun 7-1 to suit my daughter as he is monday to friday, however since then he has been awkward saying things like, what if he needs a night out and only making himself available a friday, basically so he can get rid and enjoy the rest of his weekend, so i returned to work last saturday, my mum stayed at mine on the friday- saturday thinking he would show sat, however he didn’t he was arguing eith my mother through txt last week as it’s easier if she just has her here friday, she’s not out her bed an extra night etc and he would do sat into sunday, he has a problem with this and argued with my mother from monday-Thursday last week. Now i find out today he has went to a lawyer to send me a letter, my biggest problem is that it seems to me he is picking and choosing when to be a dad and being awkward with my mother who is doing a favour, and even offered to take her a saturday IF he had a night out, does anyone have experience dealing with a lawyer? My mum isn’t available on a saturday to look after my child but i know he is, and he is doing eveeything in his power to avoid doing it, so who looks after my kid? I feel miserable it’s ruined going back to work for me (like it wasn’t bad enough) and i just feel he’s making this all about him without even taking my daughter into account, he didnt want the relationship to end and tried to get back with me several time but I wasn’t even for trying anymore.

Ps. My mother has tried to mediate as i took a step back when he removed my daughter stuff his family had bought her out of my house and refused to hand over her cot set which was a present from his mum, i went out and bought my daughter a new one as I don’t grudge her a place to sleep, as you can tell, they aren’t reasonable people.