Hi, I'd like to help you with your question.
It sounds like your husband has decided he wants out of the marriage. He has put you in a bad position by not wanting to work on the marriage. This could be a stage he is going through, or he could really want out. There is no way to be sure but there are some things you can try in response.
Ask him to go to therapy with you. Tell him that if he does want to leave, then this way you both can be sure before you end everything then end up sorry you did. Talk with your doctor about a referral, or if you attend church, talk with your pastor. You can also search on line at http://therapists.psychologytoday.com/rms/. If your husband will not go with you, go alone. You need the support right now and the help of a neutral person to figure out how you want to handle this situation.
You can also give him the space he wants. Tell him that you will give him the freedom but you want to stay married. Let him go out with his friends and do what he wishes. But rule out any infidelity. That is the limit. Otherwise, he can do as he pleases, as long as he doesn't hurt you. Treat it like a roommate situation. It is not ideal for you, but it may give him a chance to work out these feelings without you having to divorce.
Have a trial separation. See how that works. It gives him the freedom and you the time to work on your marriage and your feelings about what is going on.
As you decide what to do, make sure you take care of yourself. You have been giving a lot to your marriage and getting very little back. Go out with some friends and have dinner, get a new hair style, or try a manicure. Gather support from friends and family. Do not stay alone at home. Do what you can to keep yourself busy. If you find you are worried too much, assign a time during the day when you will think about your marriage. Then think about other things until then.
Here are some books that can help you:
Why Men Fall Out of Love: What Every Woman Needs to Understand by Michael French
How to Get Your Lover Back: Successful Strategies for Starting Over (& Making It Better Than It Was Before) by Blase Harris
My Husband Just Told Me He Wants a Divorce and I'm Totally Devastated! Help!: 13 Secrets to Manage Your Marriage (and Your Sanity) While You Deal with Your Heartbreak - Kindle eBook by Elle Peterson
You can find these books on Amazon.com or your local library may have them for you.
I hope this has helped you,