Ranting

My boyfriend of almost 4 years has a pass of cheating. I don't know if he's ever done it while with me but I know he cheated on past girlfriends. I'm freaking out. I don't know if I trust him anymore. We went from seeing each other everyday to once a week. We hardly text anymore. He knows I have a history of depression & anxiety but he says that he's there to help me & when I do try to open up even alittle to him he brushes it off or responds with " idk what to say " I feel so annoying because it doesn't even seem like he cares. When I confront him about it his answer is either " idk what to say " or " idk how to help "