Help me kill my yeast

Hello all. I have a perfect young batch of muskadine wine that I started in October this year. It taste perfect and has the perfect amount of abv. Gravity now is at about 1.028 I want to keep it here as the abv is already 12% I would like to bottle and store for a year but know there is a ton of ferment able sugars . I used Champaign or pasture red or monocrat yeast. I added 10 teaspoons of potassium sorbate and 2 weeks later still getting bubbles and with a screw top bottle still fizz when opening. How can I kill this yeast and bottle with confidence without changing any of the flavors?

What size batch is it? 10 teaspoons of sorbate sounds like a lot to me: I've usually read to use less than half a teaspoon per gallon.
I 'think' sorbate requires metabisulphate to be added too to be most effective. Meta actually stuns the yeast instead of just preventing it for reproducing. Or maybe the other way around... Either way, it's advised to use the two.

I've also heard that it's pretty hard (bordering impossible) to stabilize wine whilst it's still fermenting healthily. It might turn out that you have to let it dry out.
If that's the case, I'd advise you make a note of the gravity and ABV you liked it at, and formulate the recipe around that in future batches (i.e. ferment dry to the ABV you like, THEN stabilize and back sweeten to 1.028). If you wanted it sweet (which it sounds like you do) then champaign yeast probably wasn't your best choice.

Some people may recommend stove-top pasteurization. I don't like this technique but it's something to consider if you're desperate.

Unless you have a giant vat, 10 teaspoons is way too much.

Pasteurize