I feel like I lost it to the wrong guy

I feel super gross about myself lately, I broke up with my boyfriend of 8 months like 6 months ago and ever since I've felt super gross about him and I think of him as this idiot, but more than that I hate myself for being with him, and for sleeping with him. Everyone remembers their first time(s) as being with someone they loved and cared about deeply but I just can't feel that way. Has anyone else experienced this?