Feeling down

I'm 7 months pregnant due in December with my first child and lately I've been feeling kind of sad. I've been upset about my weight gain and appearance. I go to school full time work part time take care of a 8 month old pit bull puppy (my boyfriend went out and got after I told him no) all by myself. My boyfriend works 2 jobs and is never home. I just feel so overwhelmed. We're struggling to pay bills, keep groceries in the house, keep the cable on. The other day our dog went to the vet for a simple $40 procedure and couldn't get it done because she had an infection. The treatment cost for her infection was $300. My boyfriend didn't have the money and is looking at me to pay her bill which I did but it killed me. I love dogs/ animals but that was $300 that could have went on my baby like really. I just feel like he got this dog that he can't even afford or take care of but expects me to take care of her physically and financially. I'm just feeling so stressed. When the baby comes I know it's going to be even harder. My boyfriend expects me to take care of 2 babies by myself while he works 2 jobs and is never home I just can't. I'm actually considering living back home with my mother. I just needed to vent I guess been waking up and feeling very sad the whole entire day.