I understand your situation. I was diagnosed with ADD just a few months ago at 56 years old. I have completed 21 years in the Navy and a BS in Forestry. Look into a support group. You are not the only one who has had this problem, traveled down this road, as you have stated. A solution is out there. Find a mentor who has had the same situation and get through it. One step at a time.
P.S. The BS was rec. when I was 48.