I'm almost sure the neighbor i have been seeing a few months has been steeling my money. What should i do?

A few months ago I noticed a 100 dollars go missing from my wallet. I had left it in a cabinet at work and just umed a coworker took it. The next day though I find out that my neighbor has $100 that he said he so happened to find in his "safety vault" that he forgot about. His friends said he wasn't the type so I wasn't so worried. However, I decided to start leaving my wallet at home so that i wouldn't risk theft again. It's been a couple months now and I spend time with this guy everyday. Last weekend I was at a friends house and a lot of people were there and I left my wallet sitting on the coffee table. When I left, I unzipped my wallet just to make sure my $50 dollars was still in it. It was. That night I spent the night w/ my neighbor and he awoke at 6am because he couldn't sleep. He continued doing stuff that morning while I slept, my wallet was in my room across the hall from him in the apartment complex that we live in and my door was unlocked. The next day all of my money was gone. A couple days later we went in on food together but I told him I only had a $20 bill and that I'd have to pay him back later. He said that was fine but the next day my $20 bill was gone. I went out with him a few nights later and we decided to go in on a case of beer, he didn't have any money so he told me he'd pay me ten when he cashed his last paycheck. We got back to his place and i left my wallet in his kitchen - I'm almost positive of this. I started to fall asleep on his couch and he told me to go to sleep so I wouldn't be uncomfortable and I sleepily stumbled across the hall to my room with out grabbing anything. I worked a double that day and I asked him if he could give me a ride to work in the morning. About an hour after I got to work I realized that I was pretty sure I had left my wallet at his place and started to panic a little because I was getting suspicious. I got home at night and immediately knocked on his door to see if my wallet was in there. He said he hadn't seen it and cheerfully got up to help me find it. Of course there was no luck and I couldn't find it anywhere in my apartment either. I called one of his former roommates who is a mutual friend of ours and he told me that he had never taken money from him but that he had seen things go missing and that he refused to pay certain bills. I know that the details seem pretty incriminating but after spending so much time with him everyday for four months I believed that I could trust him and I don't want to confront him if he's not the thief because I don't want to ruin our friendship. I really need some advice here, what should I do???