Fiance "too busy" to get married!

I am a 56-year old widow (7 years) and was engaged to a 55-year-old widower (2 years) who recently told me that he is just too busy to get married on September 27th as planned.  All of the signs of ADD/HD are there - and since he stopped the clock, I have learned much more. 

A bit of background - he also has three children with ADD/HD, and two of them (twin 18-yo boys) are developmentally disabled and autistic. I know I have brought a great deal of stability into their lives and love them, but they definitely have issues with lashing out verbally and physically. Life would not be easy here. 

I made an appointment for couples therapy, because he said he was too busy to go to a doctor/therapist - he finally agreed to go, but only after getting quite angry and saying he did not have time. 

At this very moment he is downstairs working on taxes that must be paid by midnight tonight. I know he will be late, but since I checked in a half hour ago and found him trying to locate tickets for a musical with his daughter and "reminded" him - at least I think he is doing it now.

Part of me wants to run away. I feel guilty leaving but he has lied about things to cover his symptoms, spent enormous amounts of money I now know was money he did not have to spend... but I feel like the boys need me too. And how can I n he has agreed to go see someone?

Yet I am 56, and do not know if I can or should even try to walk into a hornet nest like this.

I have the option of going to stay at my son's home and relax and think for a week or two. It includes cuddle time with my little granddaughter.

Yet I feel I have a commitment to stay and get the boys ready for camp next week... I said I would.


How do I even begin to sort all this out?