Help!!!

So me and my boyfriend we will call him A well ig we aren’t dating anymore but before we dated this guy we will call him K me and him hung out I was talking to A at the time but we weren’t dating so I didn’t think it was wrong and yesterday A found out he got really mad and he said he can’t be with me Bc he thinks I’ll cheat on him which I won’t when I am in a relationship I am so loyal and I love him I don’t want it to end Bc if something from the past he said he can’t be with me now but in the future maybe I told him I was gonna wait and prove I’m loyal he says he doesn’t want to talk to me he just wants me to stay away but how are we gonna work things out if he doesn’t want to talk to me should I try and talk to him give him space should I do something really sweet and romantic and show him how much I love him

Please don’t send anything but love and advice no hate please I’m already hurting a lot