When this is you life, feeling the way you do is completely natural and totally normal. There's no reason you should be ok and feeling fine with all that going on.
Don't sell your soul for money. The toxic job will make you ill, if it hasn't already. Get another even if is less money.
The drinking husband you'll be better off without. Nobody needs that added level of stress in their life. Your romantic partner should add to your life not detract from it. Your reaction to is drinking is normal, you've done nothing wrong. It's not something you ought to be able to ignore and put up with, and it's not a failing on your part that you can't. He has an alcohol problem that he's not interested in getting help for. That alone is enough reason to leave the marriage.
40k of secret debt is another reason to leave. You don't want to be connected financially to someone who does that. You're a strong capable woman, don't stay with a dead weight who'll drag you down.
Invest in your relationship with your DC too. Even something simple like going to Macdonald's once a week for an hour or two. It gives you a chance to chat and reconnect with them.
Your injury and being bedbound, don't blame yourself for being left behind. Decent people would have accomdated your temporary disability, altering the plans so you could take part sometimes, not left you out of everything because you couldn't keep up. Unfortunately when it comes to disability most people aren't inclusive and the disabled person does get left behind, ending up friendless. Hopefully you've made a full recovery and can get a social life back. Or at least make new friends who won't hold your disability against you.
Your mother sounds like a waste of space so I'd bin off that relationship too. No point being in touch if her behaviour is upsetting you.
There are caring people out there OP and once you get out into the world you'll find some. You need some kind of hobby or social group that brings you into contact with people and that's totally separate from the rest of your life so you can talk freely to people who don't know your family and work colleagues. So the friendships can be all about you, and you don't feel eg that you'd have to not mention your husband's drinking or gambling to protect his privacy, when actually you'd like to mention that's why you feel down today etc. Go to church and hang around for the tea and biscuits after. Sign the dog up for an obedience or agility class. Join a book lovers group at the local library. Join a walking group or a swimming club. Just go somewhere regularly where there's other people doing something you can feel at least a little bit interested in, to give you common ground for conversations.