I do admire the man for his honesty. Telling you about his womanising was an act of bravery - he would have spent days, weeks, maybe even months agonising over the decision to come clean. On the one hand, he stood to clear his conscience but on the other, he risked losing his darling girlfriend, so by showing you his hand, he was taking a big chance on your capacity for forgiveness. Or was he?
Actually, maybe not! If your boyfriend was pretty confident that his dependable girlfriend would grant him immediate absolution, then the decision to 'fess up might in fact have been a relatively easy one to take. So please, ask yourself this: does your boyfriend sense you'd cling to your relationship regardless of his behaviour? I do hope not! A guy (any guy, but particularly one with a wandering eye and a groping hand) mustn't be led to believe his place in a woman's life is guaranteed. Your love for this man is clearly boundless but for heaven's sake, don't let him know this! Unconditional love sounds grand but it has its drawbacks - it leads to complacency, for instance, and in some cases to infidelity too.
So don't let the man feel irreplaceable. Make it clear to him that he's on a severe warning. One more strike and he's out! Moreover, make him see that he has some serious loving to catch up on. He can't expect to receive your trust on a plate - he must EARN it with kindness, gratitude, dependability and oodles of love. Meanwhile, try to be a little mysterious in the way you go about your life. See friends without your boyfriend, develop your own interests and don't make yourself accountable to him every minute of the day - make him squirm a little!
By maintaining a degree of independence, you'll become a stronger person and the prospect of moving through life without your boyfriend will, I hope, become less appalling to you. With luck, you won't ever need to break free, but it's important for you to embrace the possibility that this MIGHT happen - that it might be for the best. I'm afraid I simply can't guarantee that this guy will be true to you for the rest of your life. His track record isn't good, for sure, but he's older and presumably more mature than he was six years ago when you first hooked up - maybe time has helped him develop an appreciation for monogamy. My fingers are crossed.