Why is communication so hard for me 😢

I don't get it! I truly don't I try so hard to communicate with my boyfriend about our issues but I can't. A while back he cheated on me and we broke up for a while and I decided to try things again. Yeah probably really dumb of me but he's been trying so hard but it's like I still have this anger in me because of what he did. He's always asking me to tell him what's wrong or to communicate with me because he wants to know what I'm feeling so he can fix it. Sadly I can never communicate with him and this is a HUGE issue with us. He tries so hard and begs and begs and begs me to communicate with him so we can work this out but idk why I just can't we can be arguing and I just stand there and don't say a word I don't even look at him. Why can't I do this?! I have never been able to communicate in a relationship and that's seriously what has killed my relationships. Please I truly need advice. I can't stand myself being like this.