I am glad you are realizing that it may take some time to regain her trust and love. The first time my H lied to me so he could go away for a weekend with OW, the lie hurt more than the reason for it. If you have been lying for years, she will have a hard time believing what she's hearing, and I'm glad to see you are following up with action.
I also think you should involve her in the breakup. Email the OW and let your W read it. Do not use the word "sorry" in any way in the email. Just make it clear that your W and M are more important than OW is, that you will not communicate with her again in any way and this is the last she will hear from you. I know this would go a long way with me, along with total access to his cell records and all email accounts, and, coming home from work on time so I know he's not with her.