Hi MP53, some good suggestions. You seem to have made a life apart from you H but are still in love with him.
Not sure I would start D proceedings or date(least not until you are single) UNTIL you have had a real heart to heart with your H.
xplain how you feel and that although you still want your marriage to work living as you both do is a sham and you need some commitment from him to work on your marriage or you need a clean break.
Do you ever go to his apartment and are you sure that he does not have a "partner" It could be he is leading a double life.
What is his relationship like with his children and how do they feel about the set-up?
5 years is along time for a man (and woman) to go without physical relationship.
Well done on all your activities. 25 years is a long time together it is worth one last attempt to sort the problem before making a final break.