Since you entered on a visa, despite your overstay you could adjust status here if you were to marry a U.S. citizen, provided you don't have any bars to adjustment. That's a very big if, though. For example, did the government have your current mailing address at all times? If not, you could have missed a notice to appear in immigration court and there could be an in absentia order of removal against you.
You need to sit down with an immigration lawyer and figure out precisely what issues you could have. It sounds like you could be eligible for adjustment of status; don't mess it up by trying to handle it yourself.
as soon as you marry you are eligible to adjust your status to lawful permanent condition resident. should not cost more than about $4600. i am in austin, give me a call. tom