Not really getting help with the kids

My husband's job has been having mandatory overtime the last month because of so many people quitting and my husband himself is on the verge of quitting. He's salaried so he doesn't even get the extra pay. He's been pulling 12 hours shifts, 7 days a week. Then when he gets home he's tired and cranky. I've been doing my part to help him. I try to keep the house clean and stuff. Also have to send him reminders to take his medication because he's bipolar 1. But we have 4 kids together and they're all under 4. Our toddlers are 3 and 1 and the twins are babies and I get no help once so ever because of this change. I'm also extremely tired. Between being home with the toddlers and trying to juggle everything. I get no break. I'm also trying to make sure my husband takes care of himself because last time he started forgetting his medication he went manic and had to be 51/50. I know things aren't about me... But I'm really so tired. I have no help. I'm too far from my family. My husband's family is 10 minutes away but he went no contact with most of them. I'm just tired and don't know how to cope