Felt like had to do it, couldn’t say no

I met a guy that I met on couchsurfing, he was visiting the city with his parents. We had such a nice week together even though I never had considered getting interested in him cause it was such a friendly meeting and I meet people on couchsurfing all the time. He was so nice to me and he seemed like my old boyfriend who I couldn’t get over and spent 6 years with. So we happened to visit his parents room at hostel and at the end I found myself kissing him. I never meant to do that, I didn’t know why I did that cause I’m not that kind of girl who is so into sex or hooking up or some creepy shit. And at the end I kinda tried to dodge what’s going on cause the problem is I didnt want to have sex but I couldn’t say anything to him, I just couldn’t and I don’t know why, he didn’t seem like he wanted to have sex with me as well. That is my fault and I can’t stop feeling dirty. I am constantly thinking about it and it's making me really depressed to the point that I'm thinking about self harm. I really dont know how to deal with these feelings because I've been in this situation last year as well. I felt so lost and I was such in pain that I had sex with a guy who I was crying and talking about my boyfriend with. Could someone please help me I don’t think I can handle having this kind of situation anymore.