Welcome to the board you are in great hands right now with experienced people who will give you advice. Three years is a long time to be living in a stressful situation.
The good news is there is a saying here "you have been giving the gift of time" and it sounds like you have a really long time (10 years) to turn this around.
The bad news is your wife is having an affair with your co-worker and is cake eating like there is no tomorrow. Make no mistake about it she is having an affair.
If you knew for sure and had 100% concrete evidence would it change anything for you? Is it a deal breaker? If it is not stop confronting her about it.
You can't make her stop, you can't control her the only person you can control is yourself. Focus on self improvement, exercise, eat right, learn new things, take up a hobby and completely take the focus off of her and the affair.
Read up on boundaries and comeback and post some boundaries you may want to set. Don't do or say anything to your wife until you post them here first.
