It is not uncommon for new WS's to panic over the loss of their AP. It doesn't symbolize anything... rather, it states quite explicitly that you are not yet willing to let go of your AP. It is a "just in case, CYA" plan. It is, to many people, a continuance of the affair itself. If your spouse was having sex with another person and decided to keep their number around "just in case", how would you feel?
What possible legitimate reason could you have for needing to contact the AP in the future? Are you planning to meet for tea, or to exchange holiday cards? Maybe your spouse will want to ask them for dating advice or to babysit the kids? Perhaps you'll end up just being the very "bestest" of friends?
In all seriousness, the only thing you need to do with the AP is to block them from every possible way of reaching you that you can. Block their phone #, block them on social media, and send them an NC letter that states in no uncertain terms that they are no longer wanted, needed or welcome in your life and to go away forever.
If my response comes off a little harsh, I apologize. One of the first "hard truths" that WS's need to embrace is that it is OVER. Well, the affair is over, or the marriage is over (or both). If you plan on having any chance of saving your marriage, then the affair and everything and everyone involved in it has to be gone from your life. No spouse will be okay with you keeping in contact with the AP or even leaving that door open. And to be honest, you should really respect yourself enough to not want to continue down that path. But that can, and does, take some time. And we're here to help you through that. In the same way that you a wound can't heal until you pull the knife out first, you can't heal from infidelity without getting rid of the cause first.
Please take some time to go look at the "The healing library" (link at top of page) and get an idea of what post-affair life feels like, and how you can best help yourself and your spouse to move forward.
D-Day Nov '16
"I am floored by the amount of grace and love she has shown me in choosing to stay and fight for our marriage. I took everything from her, and yet she chose to forgive me."