Buying boyfriend out. His name isn't on the loan or deed. Taxes?

[Beth Cassidy]

My boyfriend's parents bought a house in cash in 2011 and put it in our names. We didn't put any money down. In 2014 I did a refi to get them out of the loan. He couldn't get approved so I put the loan and the deed into my name. Now we are separating and he wants half of the appraised equity. We are up 257,000, at the top of the market. 

How can I legally give him 128,500? What are each of our tax obligations? Will I owe taxes on money that I give him?

The house is in need of significant repairs. Can I negotiate the payout down to account for that?

Can I negotiate the payout down based on what it would cost to sell the house? 

Can I negotiate the payout down for taxes that I may at some point be entitled to pay? 

Can I use the payout against Capital Gains taxes I may incur in the future?