I refinanced my mortgage in 2010 to buy out my ex-spouse' share. Can I still deduct 100% of the mortgage interests in my 2018 taxes?

Did this involve changing the deed on the home to you solely?

Yes, since your mortgage's origination date is 2010, the interest is deductible (up to 1M of debt).  The tax law changes to the mortgage interest deduction affect mortgages with an origination date after Dec 14, 2017.  Here are the requirements to deduct the mortgage interest.  https://ttlc.intuit.com/replies/3300473