Former cheater here, albeit a heterosexual one.

My own experience was that I used every trick in the book to justify my behavior to myself and override the guilt of living with the secret. I definitely adopted the "what she doesn't know won't hurt her" attitude. I did not see until later that the closet I was living in had effects on the family that I was unable to see.

I came clean and went through the rounds of therapy and support groups. But that did little to address the underlying issues in the marriage that made infidelity seem like a good idea in the first place. I can tell you from personal experience that the temptation is always there: it's as attractive an escape from this miserable reality as any drug, alcohol, gambling, or other addictive/compulsive behavior.

A homosexual/bisexual cheater has 2 closets they are hiding inside: one for their orientation, and one for their extracurricular activities. I completely understand the self-justification and search for approval. To me, the fact that he is trying to justify it to you as a positive experience is an indication that he truly believes it was a good thing for him, for the marriage. 

If you choose to stay in such a relationship, know that you will face 2 battles on a daily basis: (1) the knowledge that he has strong desires that you will never be able to meet, and (2) he knows exactly how he can get them met with or without your approval. On his strongest days, where he feels the most committed and connected to you, he may be able to suppress them. On his weakest days, where he feels disconnected or resentful of marrying you, his mind will go right back to the memories of his days of exploring and getting the satisfaction he could never get from you.

I'm very unqualified to give you any advice one way or the other, but I think I can verbalize what might be going through his head. I don't doubt that he loves you and is mentally willing to commit to living out his days with you, perhaps even faithfully. His actions seem to match his words here. But don't think for a second that he is able to "forget" his unmet desires for men, or "forget" how easily he found the satisfaction that he craved. It'll always be lurking somewhere in the corner of his mind, and somewhere in the corner of your mind too.

M-Kate,
 There is no hard and fast timeline on navigating TGT...   some move out or kick him out and some stay for years.    My TGT/Divorce/Hell went on for 2.5 years.   I stayed in the home to be with my kids and would do anything for them... it was not financially practical to up and leave nor would it do me or my kids any good...ie Dad left, where is Dad, what did he do wrong mom?     

While a lot of advice here sounds like you have to leave your spouse its not detailed advice of how to do it. 
At some point I saw my marriage for what it was ... an abusive relationship.   I was willing to save a dollar a day for the rest of my life if I had to .. knowing one day the abuse would end.   Unseen and unknown.   

My advice remains ...do whatever you have to do ..  for your kids and yourself.  Stay, go,  No one here walks in your shoes.   But take baby steps each day to plan for yourself and kids...knowing that one day you can exit if you have to.   Knowing that the kids and yourself do not deserve abuse.   The mills of God grind slowly but they grind incredibly fine.