I need help with self care

How do others do anything for themselves? I'm a sahm with two kids and pregnant and do at home daycare. I'm so drained I've been crying for months saying I need a reprieve. I'm also handicapped physically and I am in PT OT and specialists weekly. I don't get a break the kids go everywhere with me even doctor appointments and all places. Daily tasks are so hard. I'm waking up crying multiple times a night from pain. I am overly stimulated during the day. We cannot afford help and I can't afford to quit my job. My husband keeps finding ways for himself to have self care. I even tried to just go to bed early one night or a video chat with a friend and my husband and kids unlocked the doors and were following me around. When I snapped my husband said it wasn't fair because he misses me too. I am so burned out and in pain I don't want to be touched or talked to. I am holding on by threads taking care of my paralyzed mentally unstable mother as well. My hands are so full and I'm under constant stress. Doctors keep telling me I need to rest but I have no help. My heart is now skipping beats and I'm having to go see a cardiologist now because I'm not resting. I don't know how to make myself a priority without help. My husband gifted me a prenatal massage but I have no help to watch my kids. He won a cruise this week for two but we will use it in two years and honestly I need that but that doesn't help me today for the years of neglecting myself. I cry all the time.