Advice ?

I don’t know how to explain but I’ll try. So me and this guy, let’s call him A were friends. We’ve been friends since 2016, however since we kinda hooked up around 4/5. At the end of 2018, he wanted us to have “something”, however we were not supposed to have feelings for each other, more like friend with benefits. It was all okay, like I started to like him but I didnt say anything because he was the one that said that it wouldn’t involve feelings. What happened was that around January he texted me saying that he was missing me and not in a sexual way. He was basically saying that he was feeling something for me or whatever. I was angry because he was the one that said it wouldn’t involve feelings and I was even more angry because during the time I was starting to talk with a guy, let’s call him B. So I just said that nothing would happened between us and since then were are not talkin. What happened is that I got really excited with B and kinda started to act like I liked him. I know I shouldn’t have done that but in the moment I really thought that I liked him. It’s has been some time that I’ve been feeling kinda numb. Like if I didn’t have feelings and I thought that it was because of that, that I wasn’t feeling things for B anymore. However today I saw A with a girl that I know he used to have something with and it just hurt. It was like I was holding all my feelings for him during this time and when I saw that my feelings appeared like an avalanche. I feel bad because before that I told B that I wasn’t feeling the same and he was very sad. Like very very very sad. I even think that I heard him crying. So I just brush it off and said that it probably was a phase. But now I now that it isn’t and I don’t know what to do. I don’t wanna hurt him more than I already did and somehow I feel that I should just continue and try to forget B with A.