I got bullied for demanding payment of debt

I had a sexual relationship with a guy who secretly had a girlfriend, and it went on for 11 months without me knowing about it. When I found out, I sent a private message to her girlfriend, confessing everything and telling her that I was lied to. The guy has unpaid debts to me, and so I told him that I will stop bothering him once he pays me. When I demanded him, he called me names, bullied me, and blocked me from his accounts to get away with his mistake and debt. I was told by his friend that he was already caught cheating before but his girlfriend just couldn't leave him. So right now, he gets to keep his girlfriend and swore to me that he wouldn't pay his debt. He ignores me so I can't run after him. I hope I can get advice.