Way too stressed out!

I don't know where to begin. 
1- I'm a recluse. I don't like to go out and talk to people or hang out with much of anyone. I've been a loner all my life most of which wasn't by choice. But now with my fiance's family who are very close, I'm expected to be social and close as well but I just can't. I'm not like that. So they're rude to me because I'm not like them. I've tried to explain I'm just not a people person but alas. So that creates a LOT of drama and has resulted in me basically being casted out. 
2- Finances. My fiancé is the only one who works. My 2 year old son has a different dad and our custody is 2 days / 2 days back and forth so I can't even get a temporary job (until baby is born) and expect to still see my son. So we are broke. After just bills (not fuel for the car or food) we have $100 left each month. That's it. So we struggle big time. 
3- My teeth are doing really bad and I can't see a dentist until the end of December. There is green smelly puss coming from my gums and I know that is gum disease and I brush and floss daily but it's still there and I am worried about my baby because of it. I'm scared I'll get a brain infection and go into a coma because of this. - extreme case but still 
4- Custody with my son is impossible. 2 days with him and then 2 days without? He barely gets used to one place before going to the next. It's so beyond stressful. I can't get a job because of this because I can't find sitters and I'd rather spend time with my son but my ex won't help me change the schedule to half weeks instead. So I'm stuck with this unless I go to court which would also be stressful. I'm so overwhelmed. 
5- Our car has problems, I can't use the heater without smelling burning oil or something and it's gross and I don't think my family should be breathing it. So we sit in the cold. And I worry of what else that means for the engine since it's our only car. 
6- I can't keep our home clean. My fiancé is sort of a slob but it's endearing and he's great in every other way so I do let it slide but like when I was in my first trimester, if I can't keep up.. It gets super bad really quick because he doesn't clean. He's legally blind (without glasses) so he can't see it much anyway. I feel so tired trying to keep my home clean for my son and my fiancé let alone myself. 
The list goes on but I've gotta tend to my son. I'm so tired and overwhelmed and it'll only get harder with a new baby. Ugh.