Realistically, an outside source can't wipe the slate clean for you. As a Jew, I happen to love the concept of the Catholic confession in confessional booth, and I really wish we had such a thing, but even a priest will tell you that it is not a total panacea. Forgiveness ultimately comes from within. It takes the ability to dismiss the past and immerse yourself in the present combined with the passage of time to shed shame. Shame is difficult to live with, especially in a case where you know you've done something highly regrettable. But don't worsen your shame by apologizing when the word "sorry" is wasted; really consider what the other side wants to hear first. Is an apology appropriate or is it being uttered for your own personal gain?
Trust your intuition when you sense that an apology is not going to cut it, when it will be scoffed at, when it will seem insincere or just not big enough to fit the crime. Then start forgiving yourself by beginning with a list of goals for your new life starting tomorrow. And when you create that list, focus on the things you can do for others. Begin with your immediate family and close friends who you may have neglected during a period of self-absorption. Rumination has gotten you nowhere except in circles like a hamster on a treadmill.