The souring process won't stop unless you pasteurize it. It will slow at cold temperatures (< 40F) and produce a different flavor than room temperature.
Has it been souring in a carboy? If so, place a wooden stick in the neck to allow a small amount of oxygen to enter. This will simulate souring in a wooden barrel. It may take another 6 months to reach your desired complexity.
I recommend you blend 75% sour with 25% non-sour (fully fermented). If you bottle it, I recommend 750ml bottles (with cages) since they're designed to withstand higher pressure.
Personally, I prefer to pitch:
- ale yeast + brett for primary
- sour culture (lacto, pedio, etc) in secondary with slight oxygen exposure