The ending of any relationship can be painful, even moreso when it's a marriage. However, this obviously wasn't a healthy one, despite how much you love/d him and how much he loves/loved you. None of us can MAKE anyone change. We can suggest and support, but when we chase after the other person, we're really just chasing our own tails.
It sounds to me (and mind you, I'm just a girl with a few years of college behind her) that your husband is going through a serious identity crisis. Gay, straight, in a relationship, out of a relationship, family man, bachelor, he can't seem to make up his mind.
Sometimes, you really just have to let the other person hit rock bottom before you offer a hand to pull them up.
There's something I learned as a lifeguard that I try to apply to other situations, especially ones like this:
When a person is drowning, try to rescue them. When they panic and grab on to you, push you under to stay afloat, remove yourself from their immediate area and wait for them to calm down. Explain that you're only going to help them if they relax. Approach again. But never, NEVER, let the victim turn you into a victim as well.
My instructors never meant for it to be life lesson--just a safety precaution that most lifeguards have to know to keep themselves safe. But it does apply to other situations. As much as it is breaking your heart to watch your husband struggle, you have to make sure that you survive. As long as you're alive and healthy, he still has a way to reach the surface again. If he drags you down with him, you're both in serious danger.
It may seem unfair, but you have to be the strong one; for yourself, for your children, and even for your husband. He may not ever be back in your life the way you want him to, but he will still need you. Just remember that relationships go both ways. You can't be expected to keep the whole thing running on your own. If he's not putting in his share (of love, effort, support, etc), then it isn't a relationship.
Be healthy. Be happy.
Good luck and stay strong!