Do I stay or do I go?

My partner and I have been together for 12 years & have 4 kids. He got together very young. I dealt with him being flirtatious with other women for years. We split up twice over it + him being unhelpful. His mom did everything for him, he had little accountability growing up. He expects me to do literally everything. Even jobs around the house that are typically male jobs, he doesn’t do. My dad comes over to help me get them done. We’ve had SO many discussions about how I need a partner. Him being unhelpful breeds so much resentment. I want my family to stay together but I don’t want to be perpetually overwhelmed & resentful. Makes me sick to my stomach. I guess I should also ad that he does usually try when I talk to him about it. The effort is short lived. I appreciate his willingness to try but I have ADHD and the effort not being sustained causes me great distress. Due to overwhelm and exhausting I get run so run down. As a result I end up sick every few months.