Hi Tilly ~ I know you are frustrated. And you've lived this way for a long time.
You are NOT being fair to your husband OR yourself. You are living a lie, sweetie, and it just isn't fair. Does your husband suspect? When the other woman told her husband, did YOUR husband find out?
You've put a lot of years into your marriage, and it would be a shame to throw those all away -- but what kind of a marriage do you really have? You say you "love" your husband and your marriage is "good." Do you have the kind of love that a wife SHOULD have for her husband? Do you two have a sex life? Do you two have any communication? Do you respect your husband? There can't be too much respect if you're cheating on him.

But at the same time, you're living a lie.
Why have you decided after all these years -- after 23 years! -- to finally decide that you need to "satisfy your sexual needs?" This didn't just happen yesterday. I'm sure you've felt like this for a very long time. Why didn't you make a decision to leave, or whatever -- long ago???
Perhaps some counseling would help you. It certainly couldn't hurt.

See a counselor, and he/she can help you with decisions you need to make. i wish you the very best! God bless and please take care. Hugs, Lee