I really hope you go to the appointment with him and get this all off your chest. I think it's commendable that you are keeping his illness in mind while he displays this behavior but you are not out of line speaking up for yourself.
I would be furious if my husband spent a bunch of money on some coworkers kids and then said 'it not me, it's you' after I confronted him about it.
You need to protect yourself, your kids, and your money. He may be sick but that's no excuse to put you down.