As long as coping doesn't mean sweeping your own mental and physical needs under the rug...

Been married 26y myself, in a similar situation and at the end of my rope sexually. I've had a couple of flings, was found out and officially pardoned, but a FWB would be out of the question for her.

Couples therapy is probably the way to go and I think you should tell her about your feelings about what's wrong in your relationship. If she doesn't want to listen at first it'll sink in gradually, just keep bringing it up without nagging about it...that is if you indeed still want her.