My childs other parent is terminally ill

Had a child with my ex (now 5). The relationship started amazing, got pregnant quickly and he turned quickly. Treated me badly (wont get into it but im sure you can imagine). Surprisingly we figured out co-parenting pretty well even after how he treated me. We split the week 4 days me/3 days him basically. I worked my child free days around my anti social work hours, so still not much of a break but I appreciated the freedom. Around a year and a half into this we found out he was terminally ill.

Ex became very unwell, and is now receiving full care from parents, not his fault, just life. Very young, very sad situation but I cant help feeling resentful.

Im not parenting full time, working full time and just hating my situation. I work late, i get up early and do school run or parent. I never get full time to switch off. My child is young and this feels like its never going to end. I dont even know what im looking for in this sub, just need to vent.