How to tell him he has ADHD

My therapist has just (un-officially) diagnosed my husband as having ADHD. She recognized the signs because her husband has it.

How do I tell him about this diagnosis without hurting his feelings or making him feel like we were ganging up on him in my last therapy session?

I love him, but I think he needs to know why he does what he does so we can start working on dealing with the issues.