Single Member LLC (Husband), Work from Home Deduction, Married Filing Jointly, Both Spouses Pay Rent

I own a Single Member LLC and have an exclusive work from home space, my wife and I file jointly, and we each pay half of the rent. We do not live in a community property state (NY). My question is, when calculating the work from home deduction do I use the full amount of rent that we pay, or is it based on the half that I pay?

 

Additionally, how would the work from home deduction be calculated if we were to file separately?