Hi ksheesley3,
welcome to the Apple (user-to-user) Community.
Re: don’t see it in my transaction history
don’t know how to cancel it or get the money back
Wondering if the money was actually deducted from your account if it was not accepted.
You might need to check the statement of the card(s) you use for Apple Pay.
You might also want to check in Apple Cash:
See your Apple Cash transactions – Apple Support
The "Related Article" above your question says:
"If the other person hasn't accepted the payment, you can cancel the payment until they accept it. If the person doesn't accept the payment within 7 days, the money automatically returns to you."
Else, if needed:
How to:
Get a refund for purchases made with credit or debit cards using Apple Pay - Apple Support
All the best :-)