Am I a bad girlfriend?

My bf texted me and told me he had to tell me something so ofc I agreed to talk to him. He told me that he had cancer and I don’t wanna sound like a horrible person but I have really bad trust issues and it kind of doesn’t help that he’s lied to me about things before nothing this big but he still lied to me before. I feel bad that I’m basically accusing him of lying but i just don’t know what to do...does me not really believing him make me a bad girlfriend?