Wife wants me to sleep with another girl

Me and my wife have been together since high school(10 years) and we have done a full swap twice, but haven't in a a few years. (we moved back to our small hometown) Recently we've been talking about getting back into, and have been role-playing her with another guy for the last few years. Recently she has brought up that she wants me to go pick up a girl at a bar or somewhere and have sex with, without her being there. She said she's been feeling this for a few years but was too embarrassed to say it out loud. She was very serious about this, and how she really wants it. I don't know how I feel about it, it sounds really hot but im scared it would ruin our relationship. Me and her have trust like no other, so Im not worried about catching feelings, its more so her not being apart of the activity, I feel like I would be cheating. Even tho I know its not cheating and she knows this as well.

Im really just wondering if someone else has had this type of experience. Any advice really helps!