My mortgage form 1098 shows we paid $7,546.79. There are 2 of us, so I paid $$3773. How do I enter the $35.29 (half of 70.58) earned interest on Escrow?

They should have issued a 1099-INT for the interest but some mortgage banks don't.  You can go to the section for bank interest, enter the name of the bank, the amount, and check the box for "I did not get a 1099-INT for this interest."

Unmarried couples claiming mortgage interest.

You pretty much have a choice. One can claim it all or you can split it. It's usually best if only one claims it, allowing the other to use the standard deduction.

You have to meet the rules, which are:

1. You are legally obligated to pay it
2. You actually pay it. Paying from a joint account where you made sufficient deposits to cover the payments will usually meet this standard. However, paying from your own account would be a stronger audit defense.