You have to think of this moment as the moment you get the freakiest possible and your own mind can not judge you... just get pervy with it. I don't know if I can help you with the uncomfortable and physical feeling of cringe, because I deal with the same thing sjdnjs think of finishing this part in a way that, in a future, you can enjoy it the same way as another reader; when I finish my fics, they feel more foreign to me than to my readers... so just go with the flow, even if it cringes you. Just write, no matter if it's perfect or you just can't visualize it yet or you feel very weird in the process; just write it, and later, revisit it. You can always make it better

i hope im making some sense here.. I'm kinda sleepy... but i hope this helps you in whatever way possible, not only in the smut part