Why when I opened up did my anxiety and depression worsen?

I told my professor (who was in the military) about how my home life is. It went well. I thought he was saying things I didn't want to hear, but he even shared similar experiences. I was happy to have someone willing to make sure I was okay, and he promised not to tell anyone. He just asked me to promise him a few things. But I feel so depressed right now and I don't know why.