Okay so I found out his password to his account and was tempted to go through his stuff, and if ound out that he is somewhat cheating on me or was close to it. How do I confront him without having him get mad at me for invading his privacy
I know I was wrong... but what do I do?

simply show him affection and adlib into the conversation on cheating ask his point of view and wait for his reply. If his facial expressions change while he s replying its probably a lie and you should look else where. Other wise be honest and just confront him you could always use the grapevine method

He cheats on you, and you go through is private stuff. Instead of confronting him own up and admit there is no trust in this relationship so it's over and both of you move on.