What your H needs MOST right now is people around him who will support him WORKING on his marriage and who will listen to him... give him someone SAFE to talk to...
Once that safety zone is available to him the OW won't have nearly as much of a draw...
Also, if we can get OWH involved that puts pressure on HER and gets her distrated at home... attacking the problem from both angles so to speak.
GAL is a good idea once that ball is rolling. Once your H has some safe and supportive people around him as OFTEN as possible then you can work on GAL and make yourself more inviting to both him and you.
I am worried that your state of mind might lead you to do something rash too...
Don't do anything rash... keep your eye on your goals... I am assuming of course that you WANT to TRY to save your marriage... or at least are willing to explore this...