My kids father

My kids father would always leave me at home with our kids so he could go get high. Blunts and cruises would excite him more then coming home to his kids. He would start fights and arguements or provoke me to say ONE wrong thing so he can leave and say it was my fault. I was really maniupluated into believing it too. The next day or so he would apologize and say he was going to change. He didnt work or want to find a job and would just make excuses. He did uber for alil while but wasnt consistant about it. I know he loved our kids, i have alot of pictures of him with them but he wasnt truly there to help me support them. Many times hed leave me at home with no car or money to get around i couldnt get diapers or wipes or at times had food for my daughter. I would call or text him to atleast drop off diapers or food and nothing. He was mad and it was my fault. That last month we were together my 10 month old got a high fever and he was being so fussy crying nonstop. I couldnt do anything while also watching my 2 year old and i remmeber calling my dad and he came to get us and take the baby to the e.r i tried calling my bf and he didnt answer. He didnt show up or meet me up in the hospital. The next day or so when i confronted him about it he said he thought i was lying. I was so angry at him and told him i was done trying. He always did shit like that even with my job, i would never know what to expect. I couldnt go to work because he wouldnt come home in the morning if he did i had been up all night with my son and i would start work at 5-6am or just me not sleeping because i didnt know if i had to call my parents to come watch them, etc. Iv talked to him a million times to him about this and it always "looked" like he was sorry but i realized this was my life forever. Now he is demanding 50/50 told me one week i get them the next week he does and he doesnt have to give me anything. I told him he was nuts and didnt even trust him cus he keeps weed around the house. He is making me feel guilty saying i knew he smoked and knew everything about him and now im only having a problem with it cus we arent together but no he just never has taken care of them longer then 3 hours and i always made sure he wasnt high. The last time we spoke he was demanding switching every month or 2 weeks! I asked how do u go from every week to every MONTH. my son is 10 months and my daughter is 2. Im starting to think this guy is nuts. I guess when he seen i was done talking to him he asked for 2 days out the week and he'll give me money but i told him no i was going to put him on child support and he got mad. Iv told him to come see the kids at my parents house but he refuses. He doesnt like my parents and rather not see the kids at all then to come here. He keeps asking for the 2 days out the week which i told him he could get later on if he first comes here and shows hes responsible. He says their his kids and doesnt need to be babysitted. I offer to let him take them on thursday for a few hours to his moms if he comes this weekend to see them but no. I dont know what to do anymore i told him i wasnt going to messge him anymore but he makes me feel guilty and i make myself believe like that im keeping my kids away from their dad when i know why im asking for what im asking. I think of all the good memories or very rare times we gone out as a family and it starts to make me feel guilty n it picks at me. I dont know what to do or think. I know he wont take this to court but any advice or words of encouragement can help..