I too am really sorry for everything you're having to cope with OP, losing two people you love in less than a year is incredibly hard, and if you haven't given yourself time to grieve, you really need to.
It sounds like having made the decision to try again with your husband has backfired, and isn't working. In fact it sounds like he is just another weight on your shoulders. Are you ready now to accept that the marriage is over, as he's clearly not giving you the support you need having experienced two such awful losses? If you're ready, then tell him that he needs to go, he's not adding anything to your life, he's had the opportunity to make things better, and hasn't made the necessary effort, so it's time to knock it on the head.
Then, once he's gone, tell your 22 year old that while you're aware she never expected to be a single Mum, she's lucky that she's had the family home to fall back on, but you still have a teenager to care for, and a job to do, so she needs to step up and mother her own child, and contribute to the household in whatever way she can.
Meanwhile, could you afford to take a holiday? If so, then I think it would do you good to go away somewhere on your own, and think about what YOU really want from your life at this point in time. I would suggest some grief counselling too, it may or may not work for you, but it would give you the chance to make time for yourself to actually talk about your grief, which may, from what you've said about how busy your life is, be being pushed down, and could end up making you ill.
How is your own health at present, are you doing anything to care for YOU? Do you get any exercise at all, if not, then at least try fitting in a walk in nature every day, even when it's raining, preferably go to a park or woodland or the beach if you have anything like that near you, but if not, then just go for a walk at a good pace, around the place you live in. The faster you walk, the better, especially if it's cold/raining, as you will exhaust yourself, but in a good way, and will feel loads better when you get back. Is having a bath something you enjoy? If so, then make it sacrosanct, run a nice bath with some bubbles or whatever you prefer, take a book if you enjoy reading, and maybe a glass of wine, and tell everyone that you are NOT to be disturbed. Another thing, are you getting enough sleep? If not, try and get an early night at least once a week, just one good night's sleep can make a world of difference. Finally, can I ask how old you are OP? As this would make a difference to advice that others might give you.
Sending you a big hug, you're not alone.