Need help on bringing up a sensitive topic

Can anyone offer ideas on how to bring up a very sensitive topic to my ADHD spouse? He is very private and was recently diagnosed with ADHD. No one in our family knows about it and I don't foresee that changing in the near future. While I have gotten a lot of support from books, research and forums, I feel I need to belong to a group to get more support. I am not sure if there is a support group for the NON-ADHD spouse in my area, but I would like to try to find one. I brought this up with my husband and it did not go well at all. I picked a bad time - at night after work and didn't preface the conversation with what I wanted to talk about and if it was a good time.  He thought we were just sitting down to connect. The conversation went down hill quick and ended up in a big argument. He seems fine today as is our typical pattern - he lets things go pretty easily - guess that is a blessing of ADHD. I want to bring this up again with him because I feel strongly that an in-person support group would be good for me. Any suggestions on how to broach the subject with him again?