Hello Campuslow, I am sorry that you are in your current situation. I don't think I can be much help on the relationship side, as relationships are so complex, so I will leave that to the experts. Plus, as my name suggests, I am having similar problems with relationships. But one thing I think is true, is you need to find an answer. Staying in a toxic relationship will only get worse.
So here is my suggestion for you. I believe in God (not trying to convert you), and the Bible says that God made us to be social creatures. We are most happiest when we are connected to people and to a cause. I think one thing that might bring you more happiness is to connect with other people and/or an organizations. Try joining a gym or a club, at first you might feel awkward, but after seeing the same folks day after day, a friendship might happen. A gym brings additional benefit of exercising which in itself makes people feel accomplished and happy. Or Try volunteering at a non for profit or church. Again, awkward at first but after a while friendships will happen. The nice thing about nonforprofits is that the people who volunteer are usually big hearted people. Another benefit is that when you give your time for a cause, you usually feel better. Lastly, try taking a class or a sport or a club at your local community college. Anything you can do to see people day after day usually helps builds a networks.

I wish you the best and please don't give up.