Boyfriend texts ex

So last night I was messaging with my boyfriend and then he said that he was tired and felt terrible bc of past situations and that he’s trying to fix burned bridges and broken relationships. When I tried to ask him about it he said he didn’t want to share that with me and maybe he’d tell me in the future but he felt like a terrible person. Well tonight I found out that he messaged his ex girlfriend last night and had a full conversation with her when he told me that she cheated on him and was awful. I just don’t understand why he said he felt like a terrible person why he won’t tell me and why he messaged her. Am I just being a crazy jealous girlfriend?