Agree, it will be painful and could cause issues. Considering you are pumping and not nursing (ie no baby to battle) it should be easy enough to drop a pump session a week, or at least every 4 days or so.
I stopped very gradually, and it went well. Try dropping one session per day, every 5-7 days. When I got down two 2 session per day, I just gradually increased the time in between the two sessions and this worked well. It has not been 8 days since my last pump, and I haven't experienced any pain/engorgement. I would pump when you feel full to prevent mastitis, and I also think it is easier on your body hormonally. My best to you!
I went cold turkey and it was OK, but maybe I was just really lucky. Every time I was too uncomfortable I manually expressed a little, just enough to make it bearable. I didn't get mastitis or plugged ducts. It took a few weeks for the supply to go away. It was rough for a few days but not much after that. I didn't like the idea of continuing to pump because I would have to dump it and I just wanted to be done. I stopped because of my son's food allergies and I had taken too much Fenugreek for the hospital to accept my milk as donation.
Re: Can you stop breastfeeding/pumping cold turkey?