HSA accounts are individual accounts and eligibility to make an HSA contribution depends on the individual account holder's health insurance coverage. Your wife's Medicare coverage prevents her from being an individual eligible to contribute to an HSA but it has no effect on your eligibility for you to contribute to your HSA.
See IRS Pub 969:
https://www.irs.gov/publications/p969/ar02.html#en_US_2016_publink1000204025
("You" in this reference is referring to a particular individual.)
