Question??

Hi, so I was wondering. There are many cultures in the world that disapprove sex before marriage. Specially in Christian faith. I am a Christian and due to certain choice I made when I was young, I had sex with my boyfriend. I tried so many times to pray and let it go but i really cant stop regretting it. It’s like a constant reminder that I Hadley down God while he’s been there for me in every way. I haven’t had successful relationships after that. I’m 28 and don’t see the marriage wagon soon in my life. Is there anything else I can do to help me move on? And I’m scared that whoever I meet won’t take me seriously because of my past relationships.