Pam - I think there are two kinds of love in a marriage. One is a "selfish" love - the part that wants the spouse to love you to make you feel good, that's angry if they don't give you that love that makes you feel good. This is often the place where the anger of betrayal comes from - they went away and took away those good feelings you got from being loved by them. Holding on to the "selfish" love isn't good for you, or particularly helpful to DBing efforts either for that matter. "Forgiveness is a gift you give yourself" is connected to this. Some of your continued "love" for D is really just connected to this pain and maybe to the fact that you haven't quite built your life up to the point yet where you are receiving those good feelings from others.
Then there's another kind of love - unconditional love. When a parent has a child who misbehaves, you don't stop loving them. You may be angry with them, you may enforce consequences for their behavior - but you still love them, even when they stamp their feet and say "I hate you!". I think some of what you describe feeling for D falls into this category - that despite the awful way he has betrayed you, you are still concerned about his welfare and happiness - a kind of "selfless" love.
The trick, of course, is to free yourself of the "selfish" love, while allowing yourself to continue to feel the "selfless" love. Feeling the "selfish" love will only hold you back and keep you in the drama and the mud; feeling the "selfless" love does not hold you back or bring you down.
It is so much easier to do this when you fill the holes in your life, wherever they are, so that you no longer feel like you "need" your spouse or ex to fill those spaces for you.
