Telling your boyfriend you had mixed carriage?

About a month ago, I got back with my boyfriend we gave each other a break because  I been going through depression didn't want him to feel bad about the situation. We had unprotected sex and I didn't had birth control for almost a week. I didn't take a plan b because I thought I would not get pregnant. I took a pregnancy test a week ago and it was positive but today I been bleeding a lot. I think I had a miscarriage. I had one before a long time ago and it's the same way.
Should I tell him what's going on? His been moving from apartments and we been arguing about why I decided to give it a break. He thinks I am gonna leave soon. I wanna stay but I'm not sure if his gonna believe me about my miscarriage, I'm not sure if I should tell him or just try to move on and fix our problems? Help please.