Child support

I’ve been separated from my daughters father for 2 years, my daughter is 4 this upcoming January. I’d say my daughter is primarily in my care and I’m her primary parent (makes decisions, takes to doctors, dentists, basically everything falls on me) we’ve never gone to court. We separated at the pandemic so everything was shut down… I know I need to go to court to get our custody agreement on paper. Anyways, I feel guilty when I think about child support… im struggling financially, I am sick and have been put off work for the time being so my take home is dick all right now. If I was in a good place financially I’d never think of child support but it crosses my mind and it makes my gut turn. He always makes me feel guilty or bad like im a horrible person when I ask for anything… I’ve asked for participation in groceries, diapers, wipes ect. When he shuts down going to court and getting a custody agreement and talk about support. Maybe once or twice he’s grabbed a few food products, I’ll give him that. Now that being said I want to add that he acts entitled. That the world owes him and he owes nothing back… it’s his way or no way. When he meets halfway to pick our daughter up it’s at his time choosing and there’s no bending or he expects me to take her to him… he gets to pick and choose when he wants to have her… he will go a month without seeing her then consistently pick her up for a few weeks on the weekends or every other weekend. I wouldn’t say he’s a shit dad but the consistency isn’t there and when he does want to pick her up after not seeing her for weeks she becomes resistant and freaks out when she leaves with him. There’s even been a few weekends where he’s picked her up on a Thursday night til a Sunday. He has another child with another women and the child is 11 years old. He pays her support, he picks and drops the child off, he takes him to appointments, he pays and takes him to sports, he’s more consistent with visitation when it comes to him. It just sucks that because I feel like anything in regards to our daughter or a an inconvenience to his life and it’s not that way with his other. I’m not an unreasonable person, I’m not rude to him and I don’t try to make his life hell. I do things to help him, I bend to benefit him so he is around more.. he’s so bitter and rude. I just don’t get it anymore… she had to be sedated for an oral surgery and it wasn’t fully covered on his insurance so the agreement was that he paid what wasn’t as this was necessary procedure… I want to add when we sold our house he walked away with 60% of profit and everything that was in the house. He’s now selling everything, including the brand new appliances and couch set we both paid for so I didn’t feel bad that he was left with the balance of what would be owed. It’s a couple hundred bucks.. the dental office contacted me and said it needs to be paid ect he was supposed to pay it weeks ago.. he told me he was so I asked him what was going on and he got so hostile and defensive like it was my problem not his… again everything falls on me. I can’t afford it but I’ll figure it out like always… tell me why I feel so guilty when I think about going on support. It makes me feel sick.