Oh, wow! I went through almost exactly the same thing 2 years ago, but with a then 13 year old daughter. My now ex-husband had become abusive, both verbally and physically, then decided that he was done being married and being a father. He left, but wouldn't come get any of his things and move out. It was incredibly painful for my daughter and myself, as he would occasionally come home to get one or two things, then be gone again. Here's what I did. You decide whether it will work for you or not.
1. If you have a separate garage, pack up everything you would say is "his" and put it in there. Make sure anything you don't want him to take is out of the garage first, because you want to make it as simple as possible.
2. Get your locks changed on all doors of your house/apartment/condo.
3. Tell him that if he wants to keep your car, he needs to get a loan to pay for it, or return it to you so you can either keep or sell it.
4. Find someone else you trust to watch your kids, and set up visitation for him. This part will probably be tough, but you really want to set boundaries with him.
5. Get online and find the paperwork to file for legal separation and child support.
Here's a link: http://www.courts.state.co.us/chs/court/forms/domestic/jd...
The fact that he pays child support to someone else already and has "very little money" is no longer your problem. I know that sounds harsh, but you need to think of yourself and your children now that he has decided that he doesn't want to be a full-time part of your family anymore. He needs to either get a better job, or work a second part-time job anywhere necessary in order to pay for the things you and your kids need. If you're really not sure if he is done being married, offer him a choice. Let him know that if he's serious about leaving permanently, you're going to file paperwork with the courts and get child support set up. If he still wants to work on it, you'll set up counselling. My ex chose counselling, then changed his mind the day before the appointment. I packed all of his stuff and told him to come get it. He has since said that was a HUGE reality check for him, and it made him grow up really fast. We've been legally divorced for over a year now, and are both in new relationships with other people. We get along great now, have salvaged the friendship that caused us to get married in the first place, and are actually going back-to-school shopping together with our daughter on Sunday. I NEVER thought that would happen, but God took care of all of us.
Good luck, and we'll be praying for you!
DJ