<human>: I am very upset as my boyfriend of almost 3 years (both 19) has been cheating on me multiple times. I've accepted all of his apologises because I actually did love him - and still does.

After a long healthy period in our relationship there are now again many signs of him acting weird. Some of my trusted friends tell me he has been cheating on me again, and even a girl I vaguely know accidently told me she has been sleeping with him while we were together. I also once caught some of his ugly text messages to some girl.. I've had enough.

I just want proof so I can end this. I'm ready to move on, but only when I'm 100 procent sure of my accusations. I am both and furious and upset as fuck guys.

So detectives of Reddit, In which clever way can I check his Facebook chat logs, as I am almost certain he's currently chatting graphic stuff with some ugly bitch.

* He's very careful about logging out when using my computer.
* I know his email adress, but none of his passwords
* I don't want him to know, so resetting password is probaly not a good idea. 

If shit gets serious, my friend talked about a key logger or something, but I don't want ot break the law or anything.. I guess.

Can you condense the text into three sentences or less?
<bot>: Boyfriend is cheating scumbag, help me proof his scumbaggery by accessing his facebook in clever ways.