If you love your husband, don't tell him. You will be hurting him.
I've often thought about this theory...hurt someone else to lessen your own guilt.
I can't honestly say I'm in favor or against...I just know for me, my marriage is built on honesty and we don't keep secrets-not that big, anyway. I just don't think I'd be able to go on while my husband had complete faith in me and thought I had never done anything like that. I would partly feel like I was making a fool of him, his faith and confidence in me being so misplaced.
And I'd nevr get over the guilt unless I worked it out with him. So for me, it would be the option of being miserable my whole life while he assumed all was well, or 'sharing' the misery, so to speak, for a while until we can heal together. It probably does sound selfish, but I'm not sure I could go the other route. Our marriage would eventually suffer from my guilt, and I'm sure I would start acting out somehow...to make it eventually come out. And I'm not sure 25 years after the fact is better than right when it happens. Then the spouse will really feel like the marriage was a lie.