Forcing people to do something (or even making strong suggestions) is usually not very effective. I think the best you can do here is: (1) make sure that you guys have fun doing something together (not necessarily scuba) and (2) increase the opportunities to dive should your husband want to try it out again. The male ego can be a fragile thing. Hopefully, your husband doesn't let it stand between him and fun sport. I don't know how things play out when the two of you go diving, but it would probably be a good thing for him to set his gear up by himself. There's a routine that every person develops, and this is critical to becoming an independent diver. I've witnessed how some spouses set up scuba gear for each other. That's a big mistake, in my opinion, when the other person is still learning how to do things on his/her own.
I'd recommend that both of you check out a local dive club (or two or three).
Expand your circle of dive buddies and the opportunities for diving will increase.
If your husband wants to dive, he'll certainly have the opportunity to do so. The more he dives, the more comfortable the activity will become. A scuba refresher course might also be a good idea. If that's something he wants to do, he should ask around and find a good instructor.
I like Thalassamania's suggestion to take a Fundies or Essentials GUE class together. It could be a wonderful bonding experience for the two of you, and you'd get to learn a lot of useful diving skills in the process. What's not to like?
Does your husband have any other leisure-time activities that he enjoys doing without you?
If so, I would think he'd understand that's it's OK for you to go diving with others. In fact, I think it's healthy for your development as divers to dive with other people. You'll learn new things that you can then share with each other later on.
Good luck with everything...