You will have to let her stick to you if she die die don't want to break up, no choice unless you want to take the risk that she look for your wife.. if I were you, meet up less often and gradually lesser frequency. Take yr time to reply her msg or try to give excuse not to meet up. Do not totally avoid. When meet up, no more lovey dovey words and no need to be nice to her. No need to be nasty or angry, just be cold and give the bo chap attitude. You may have to tahan this for a long long long time until she sian or cannot tahan your change. It may be a marathon. Only then you bring up break up issue again and of course on and off, you can broach this issue at the right time. Whenever she threaten you to tell your wife, you just have to tell her it's ok no problem you are prepared for it (i think you have to take a gamble on this) as I think she knows she is holding this ace card. If you dont remove this, you will always be on the loser side. Let her know if she does that, it will be tit for tat and immediate ending for you two. No matter what you two can never be together
My view is do not up her even if you are horny or let her up you
if you are not careful and she got pregnant, you will be dead meat. Again find excuse not to do
Wish you good luck and if eventually you two break up amicably without affecting your life and family, do give her a parting sum as she is with you for 7 years and you enjoyed her raw pussy