We have one DC. We had the agreement that he pays £60 p/w maintenance (he is paid weekly) and we split some costs by half - like DC bedroom furniture, school uniform ETC.
We have been on and off a couple of times since DC was born - and we have been trying to work things out this year, but have had issues with him acting suspiciously around his phone, amongst other things which make me doubt he is being entirely loyal to me. Either way, I just don’t want to be in a relationship with him or ‘try’.
The issue is he controls contact with DC and money every time I try and speak about the fact I don’t want to work things out between us. He usually refuses to engage in the conversation, is quite rude, and often storms off and drops out of his next contact time with DC. For example, I tried speaking to him yesterday (he was meant to have DC yesterday PM and all day today) and he stormed off and I haven’t heard a word from him - so I’ve had to cancel work I was meant to be doing today due to lack of childcare 
He seems to want me trapped in this horrible limbo, where we aren’t together but he wants access to mine and DC’s home and wants to essentially play happy families at his convenience, while essentially having the freedom of a single, child free man when he feels like it.
So AIBU to ask for advice on how to handle this? I really don’t want to be in a relationship with him - ideally I’d want set times we each have DC, and for us to only be in contact regarding DC. Whenever I put this boundary down and stick to it, he usually fucks around with contact timings, is often late with providing the money we agreed, and is generally as difficult and unpleasant as possible. I hate to admit that it makes me think it’ll be easier to just go along with us ‘trying’ to make life easier and avoid the financial strain. But I guess that’s exactly what he intended me to feel!
this situation is really starting to get me down.