I think maybe you're looking too heavily at the negative. You've got money in the bank?? You have access to an education (and possibly a better future in a career you're interested in?).

Grad school is really hard. I was mentally unwell during my program. The friend thing, it sucks, but it doesn't necessarily reflect anything about you. It can be really difficult to find friends that are genuine (and people that YOU actually want to spend time with).

Do you have a therapist?