Firstly, don't have the affair. It's just sex and the battery operated option is best. It won't expect anything from you for a start and it won't tell your colleagues in the morning.

Then, ask OH how he's feeling about your marriage. Listen to his answer without putting your thoughts forward. When he's finished, tell him how you feel. Not in a way that accuses him.

It might feel odd to begin with, a bit stilted and fake, but once you get going it will be OK.

If he won't take part in this conversation, you have two options. Put up with life as it is, or tell him that either he talks or you walk.

As for the sex part, don't bring his performance up until you've decided to work at the relationship. As part of the "new us" you can introduce new things to your sex life, ask him for what you want and if necessary show him!

Good luck.