County Suing For Property Taxes On Deceased Parent's Old Property

Hello, I'm completely law illiterate so apologies if I use the wrong terminology anywhere on here.
Long story short, years and years ago (2009?) my mom used to own property in East Texas, presumably alongside her boyfriend at the time. They broke up and she and I left the property, leaving the boyfriend with it. I was a freshmen in high school at the time so I had nothing to do with the finances on the property and have no clue if she followed any proper procedures on removing herself from the deed.
About 8 years ago my mom passed away suddenly. No will or anything. My older sister handled all of the taxes and finances involved with her death.
Cut to today, me and my siblings have been served a suit against the county to collect delinquent taxes on the property demanding we respond within 20 days. None of us are interested in the property and we certainly can't afford the amount they're demanding. I know the correct answer is simply to get a lawyer to walk us through the process, but I'm hoping someone smarter than me can help sort through what options we have.
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