More a tech support question, but since nobody replies to that (except me and perhaps 1 other person).
Anyhow my friend had the same. He was, like you, stupid enough to have Steam and Mail as the same password. Unless your computer is infected then you're not stupid, then you're just unlucky and fucked in the butt.
I'd advise you to personally contact Steam Support per E-Mail. Make a new email account or use your secondary mail (if you have one. If not, make one).
If you need an account to contact steam support, make a new account on Steam.
Steam support is notoriously slow, so don't expect at least a reply to coem your way within a week. It is not possible to call steam directly by phone.
In any case, explain your case in the email in meticulate detail. Then, do whatever they tell you to do.
I will be honest here. There is a chance you will not get your account back. This is a more common issue than you think, but the chance of you getting your games back are slim. Be prepared to be extermely disappointed.