I know all about it. I'm 23 weeks and have two jobs and work 7 days a week. I resent anyone (especially customers and fellow staff) just for being alive and not the pregnant tired one around me.
I'm wondering: do they know you're pregnant? Because heavy lifting is a huge no-no. I'm a waitress and I found out I'm not supposed to even be on my feet for more than 4 hours carrying trays and buspans. I know the stress of not being able to quit because you need the money and there is no other way.
I hate leaving the house too, but what's helped me(and it's hard to do, believe me) is to MAKE myself go to a coffee shop with a book. Even if the book is boring and there is no one to talk to, I find the fact I was able to force myself out really helped for the time being.
Do you live in Canada? Because if you do(not sure about employment insurance elsewhere) you could take sick leave soon, then a year maternity leave after. See what resources there are for that in your country. If you take leave now you can maybe find a good support system of people to help the hopeless feelings not take you away forever.I hope this helps a little.