Sometimes when I need a fat cock on short notice, I have my husband wear a thick silicone sleeve. He can't feel anything but a vague tightness of my pussy wrapped around it, and I get fucked the way I need.
You need to do more than just admit her pussy is better than yours. You need to say it out loud. "She's better than me in every way. My pussy is useless". (I did a fun sexting session with a cuckquean!)