Does anyone feels afraid to be in a relationship just because u can't get over the last one?

sooooo my last relationship wasn't an examplery relationship. My ex lied to me and he had some other girlfriend too other than me and when i confronted him about it he refused it simply and instead made me feel guilty for asking even tho i had proof that girl and my ex are together. But i connected with my ex on a different level, i shared with him everything my day was incomplete without talking to him and he was rich but again dishonest. We broke up as he was getting engaged to one of his cousin. And now i am too afraid to be in a relationship. Few months back my first crush ever wanted to be in a relationship with me and i was excited at first but after a few hours i got panicked and made up a story that i can't be in a relationship with him and blocked him.Few days back i unblocked him again and he still talks to me like he is not at all pissed off. He treats me so good and respects me but i am unuable to love him to give him what he wants and i feel so bad about it. I am so confused