Use of husbands surname.

I have been married for 5 months and never changed my name. We are already getting divorced so I had started the process but never finished. We bought a house shortly into the marriage and the mortgage is in my maiden name but the title has my last name as his. Is this illegal if I had every intention of changing my name, but then didn't because a couple weeks later the marriage already went sour? - Is this your question? Add additional information