There is a lot of regret in your story and I hope that either you both can learn to love again or simply move on. I am sure the last three years have been long and traumatic to you and you have learned to get used to (or comfortable) with what is going on in your relationship. Now that he has a change of heart, he just wants you to jump aboard his train. Well, you have already did things HIS way by not having sex or really a relationship so there is a lot of making up to do.
There is a chance in every relationship and maybe marriage counseling would be helpful in yours. Your relationship would have to start fresh and new to recreate a relationship that was lost when you got married.
Can you keep us updated on your situation? You along with many other posters on this subject will help along the way with others. I hope your situation will also help others. Good Luck!