I haven't filed taxes in the past 3 years, what should i do, i'm sure i owe on at least one year?

You need to correct the situation as soon as possible, by filing returns for each missing year as soon as you can and paying as much as you can of any amounts owed. You may be best advised to get a good tax CPA to help you, but even if you file them yourself it should still be better than not filing at all. Try to be as complete and correct in preparing each return as you can, and make sure you file on time for the most recent year. If you wait until the IRS catches you, it will just be a worse mess. If you come forward on your own and immediately begin taking steps to try to correct the problem before the IRS notices one, then it puts you in a much better position to ask for and be granted any breaks you might be able to receive.