I would go to the event, alone, tell your wife that her behavior excludes her. She has to know how she affects other people; you, your friends, anyone she comes in contact with. You can still love her, stand by her, honor your marriage vows; that's all about YOU, not her. But it is the difference between who you love and who you "like", we hang around those we like and they may/may not coincide with those we love.

But unless your wife gets the "truth" of how her behavior makes you all feel, she can't improve it? You and she are not "stuck" unless you want to be. You do the best job you can and if it affects your health, you have to back away; you are in charge of keeping your organism alive and growing! If you have "extra" you help others and if you have a "partner" you work together. But if she isn't doing her work, isn't "trying" as hard as she can, isn't growing and changing and smiling at others and sure of herself (so you don't have to leave early), etc. then she can't play well with others yet and won't be invited/included.