Yup, YOU back off, let your support team blast him every time he contacts them...
I would STRONGLY suggest you get your own private account. You don't want him taking money out for illegitimate things since you have little recourse if that happens.
You don't need to tell him about the account. This is important because being with addictions are NOT in the state of mind to be organized or careful and they tend to let money run through their fingers and they WILL resort to stealing it if they have to. I have read posts on this forum of WS husband's actually taking out mortgages on their homes - putting wife and children into financial hardship - in order to buy thier OW very expensive jewelry.
Protect your finances. Keep the account you share, but get your own account that you have privately to put anything major into.
It's ok to keep using the shared one, but don't put anything in there you don't mind losing. Particularly now with WH destitute, he may at some point ask to borrow money from you, short change his children on support, or resort to stealing. I know it sounds horrible, but it does happen.. seen it more than once. Your H is just very vulnerable to that right now. The last thing you want is to end up in a huge fight with him over the legitimacy of some mysterious withdrawals he's making...
You keep focussing on your school work. Try not to share financial details with him. While a spouse is cheating I don't reccomend the LBS share any info that isn't to the advantage of the marriage to share. If him finding out you make more money is going to reduce YOUR support payments and therefore INCREASE HIS income THERE then keep it a secret.
You can always take the extra and put it into an education fund for his children. So if you are making say an extra 500 a month just put that 500 into savings for kids college and keep accepting H's support payments. If he DOES find out that you make more money you can always tell him you have'nt spent a DIME of the excess...
Ignore your h's claims about what he's planning or hoping... he's addicted right now.. its the same as listening to a complusive gambler promising "I have a sure thing coming up.. I promise.. its comin and I am gonna win big very soon..." Its just his own desperation coming out...
This 24 - year old woman will not put up with his BS for long once the money stops rolling in. I am sure the business start up was exciting for both of them, but with it going down the drain you will likely see the affair go down with it... Honestly between his inability to cover his costs and keep his head above water, and their immaturity at cheating in teh first place that relationship is NOT giong to last long term.
Either she will get sick of his immaturity or he will tire of hers. I am sure she has a lot of growing up to do as well and he will start to see that more now than he has in the past. Affairs DO end, but reality takes time to sink in. Unless something drastic happens it will take them a few more months yelling and fighting before that falls flat. Eventually she may move in with him to save some $$$, but when THAT happens the affair will just fall apart all that much faster.
Rather than thinking and hoping HE will come back. You need to work on your boundaries of what you are willing to accept WHEN he comes back. If he just show up on your doorstep and wants back in no questions asked (and he will try that at first) you need to have yourself prepared to push back and tell him "NO".. and send him on his way.
Just becuase he returns broke and humiliated does NOT mean he's grown up and won't do it AGAIN.
You need to set your requriements for him to re-enter the marraige. Especially with you growing up yourself and working on yoruself and your children you will likely develop a higher standard in a mate for yourself and a parent for your children too... right now I suspect he is far below the bar for that.
If you focus on what you need from a partner - bare minimum it will build YOUR confidence and help you set some healthy standards for your marriage when he returns.
I suspect he will return in the next six months or so if his financial situation keeps worsening.
