He doesn't sound very reliable. I think maybe you are wise in keeping your distance. Getting involved with him again would include bringing him back into your children's lives which might not be the best at this time. You might want to discuss this with a therapist before you make any rash decisions. You have to think of your children and what is best for them. Of course, this is just my opinion and doesn't really count for much, so take what you like and leave the rest.