Do I only enter 1/2 the $ amount from my 1098 box 1 since I shared equally the loan with another person?

You enter the amount that you actually paid yourself.

Assuming both of you own the home and both are liable for the mortgage each of you should deduct the amount of interest each of you paid. 

CLARIFICATION: You enter the amount of interest that you paid. If you paid half of the mortgage payments, then you enter half the amount of interest shown in box 1 of the Form 1098.

@bernadettramirez , generally ONLY persons on the loan document and on the title of the property can  claim the  interest expenses as a deduction  ( even though with all the limitations  under the current laws , most people  tend to use the standard deduction ).  So in your case if the 1098 only shows your name  but the other party is on the loan document and on the title deed, then you can share the benefits/deductions in anyway  you like  ( there is no requirement that one has to deduct the whole of the amount shown on 1098 , but cannot be more than that shown ).  Note that state laws may modify this.

Does this help or did I misunderstand your question ?