Breakups & Divorce Support Group
Just broke up with someone or in the midst of a difficult divorce? Breaking up is difficult no matter what the circumstances are. They say that time heals all wounds, but sometimes a listening ear or a hug can work wonders for the heart. Whether you need a place to vent, someone to hold you to No Contact, or need advice about what to do, we're here to help.

Stop worrying about him and think about your children.
Also know that you can't force someone to be a parent. My step-son went through the same thing, when he married a single mother and they had a baby. She left a note one day saying that she wasn't done partying and experiencing life.
She abandoned him and the kids, and never came back.
The best he could do in that situation is the best you can do. Get child support. If he doesn't pay, then report him and he can think about it while he sits in jail.
Maybe he's got some mental health issues of his own, but you can't fix him. He needs to either straighten up, or face some kind of consequences.
Stop forcing the kids to visit him.
Not every man who can knock up a woman has the capacity to be a dad, and not every woman who can get knocked up has the capacity to be a mom. It can't be forced, and it can't be mandated.
See the situation for what it is, and do what is best for your kids. Best of luck.
I wish you all the best.
The other thing you may need to do is get a formal parenting plan filed with the court. It should spell out how much the children should spend with each parent, what days. what the pickup/dropoff times are, which holidays, etc. In Oregon, child support is calculated based in part on how much time the children spend at each household. Mine is pretty simple, two weeks with me, two weeks with my ex. (50%/50%) pickup time is at 5:30 pm Friday or whenever school gets out. Now that my son is older, he just rides his bike over to her house after school.
One thing I wish I had done, was spell out all the major holidays and put them on an every-other year rotation. Because of the 2 weeks on/off schedule, almost all the major holidays fall on the same parents time(mine), and we have to negotiate who gets our son for each, every year. That makes it hard to plan ahead when my ex waffles back and forth on it.
Anyway, getting it all written down and filed with the court formally means that if he keeps backing out, and you get tired of it and want to take action, you have some amount of recourse. You will also be able to say that it's out of your hands; he agreed to a visitation plan and the court expects him to follow through on it. You will have to document it when it happens, and keep a running list when he fails to pick them up. Unfortunately, about the only solution the court may offer is to say you don't have to take the kids over to him anymore. I have not had this problem fortunately, however I know a friend of mine did, and she kept a running log of every pickup and dropoff, and ended up having to take her ex to court over it, (he ended up owing her more child support because they were at her house 100% of the time).
As far as constantly reminding him of stuff, just let that go. Tell him once. My stbx needed to be reminded of everything, multiple times, and he'd still "foget". I couldn't imagine how he could forget everything. I finally came to the realization that he "forgot" things on purpose, because he didn't want to do them. It wasn't my job to show stbx how to be responsible, it was my job to show my CHILDREN how to be responsible. You kids' dad will miss out on their lives, and they on his, but you can't let yourself be put in the middle of trying to remedy this. Sounds like they are not a priority in his life, you kinda have to accept that. You can't make him care more. Build them up, and figure out a way to let them know the truth, that it's not their fault that their dad isn't around so much. This is hard, but you'll figure it out.