I wouldn't talk to or voice relationship problems to the opposite sex unless you are 'single'. It is a big no-no.
I also wouldn't spend too much time with this other guy while your viewing your H as 'pathetic'. It really does not give him any chance at all.
You may attempt to bridge the gap with your H and pull away somewhat from your co-worker. As long as you want to stay up on your co-workers, you will always be a spectator in your own marriage and it will never work.
