I need help to heal

Hi, I’m in a really toxic relationship, but I’m afraid to leave her because I’m scared of being alone and worried that I might never find anyone else. Every day she hurts me, but it feels like I can tolerate the hurt more than the loneliness.
What should I do?
If I don’t talk to her all day, she starts a fight. She needs constant attention, but I’m feeling overwhelmed. She shouts at me and always thinks I’m the problem. My mind keeps going back to the first 3–4 months of our relationship, when she was different. I truly fell in love with her back then, but now I don’t see anything that can help us.
I want to become mentally strong, but I’m struggling. I’m in San Jose, California. Is there anything I can do to feel better or build a life that helps me heal? I don’t want to jump into another relationship because I know the cycle will probably repeat.
How can I heal? I’m 29 years old, Indian, and I’m wondering if there are any groups or communities I can join to meet new friends. If you’ve been through something similar, I’d really appreciate hearing what helped you.