Shady potential fraud and thievery (long)

Not to beat a dead horse, but resolving debt by letting someone play on your account is asking for trouble. I gave my friend my Party account info to let him play. He did, he lost, he gave me what he lost. Fine so far.
Couple days later suddenly there's about $70 discrepancy in the account. I asked him, and he said yeh I played a few tournaments last night. Now, he gave me the cash right away, but that's not the issue. I don't want to log-on just before a tournament I thought I had enough in which to play, find it's no longer there, and don't have free cash to throw in just then. He also played a few FPP freerolls w/o consulting me.
He gets pissed at me because I decided to go ahead and change my password. In short, think long and hard before you let someone play on your account.