Husband wants divorce due to guilt for cheating.

We've been together 17 years, since HS. We have been an exceptionally close couple, and now have a special needs 11month daughter. He was always been faithful until 3 years ago, but now has a history of cheating off and on with the same woman- usually about a year between episodes. I want to forgive him for the sake of my family. We are great together except for the cheating. I believe our daughter needs a loving family. 
​However, he won't forgive himself. He has a remarkably high libido and believes he will cheat again. Therefore he wants a divorce. 
​Any advice, that might help us stay together? We are truly still in love.