Engaged to someone with ADHD

I have been dating my now fiance for almost 3 years now. It has been some road, let me tell you! During that time we have argued, more about him being impulsive, and unable to save money. His diagnosis came 3 months ago, when I pretty much said,"if you dont go and talk to a professional, I am out the f***ing door." He went. The diagnosis hit me like a ton of bricks. I was upset that I didnt force him to seek help sooner. I was upset that his parents never questioned it for him to have been diagnosed sooner. But most importantly i think i was upset because I said some really horrible things over the time we were together... and he was really and truly not the one to be blamed for all this. I soo wanted his therapist to say, "nope, u need to get your act together." but what did he say after  the weeks of gathering information from my fiance? ADHD! So I cant really blame him anymore can I?

My issue with FH is his inability to save money. For me its easy breezy. You make $100/wk, save $10 and you have just started saving. For him, he cant. I say "cant" and not "wont" because he does try, (he cant be that good of an actor... or is he) but it always end miserably. if he says he will save 1000 this year, he may only save 200. So you can imagine where that leaves me now.

Trusting him to save money is not going to work. It will backfire, and I have learnt the hard way. I need some help on ideas on how to get him to save now leading up to the wedding, and also long after we are married. I am fully aware that financial hardships are one of the biggest reasons for divorce, so bring those suggestions. :)