At your size, rollers would be a bad idea.

Get a good mag or fluid trainer, whatever your budget will allow. Consider looking for a used one on Craigslist.

Put a slick or smooth tire on the rear tire of your MTB and pedal all winter long.

Yes, they can be boring, however, music helps me. And I've been known to do 2 hour sessions on the trainer. Intervals definitely help during long sessions and they'll be good for you come next season. Definitely consider a fan. Otherwise you're just dripping sweat on the bike and below.

FWIW, I'm in WI too (Milwaukee, south side). This year rather than being inside I believe my trainer set up will be out in the garage, so I'm going to need a heater. I'm also contemplating pulling the trigger on Sufferfest or something similar. Laptop, speakers and my goals. I don't know ... I find winter trainer riding somewhat therapeutic. It beats sitting around idle all winter. But when spring begins to arrive, I get antsy and tire of the trainer.