Still thinking...
Kendall-who-is-NOT-finished,and others facing such a painful decision-

One big reason people with arthritis are encouraged to continue playing an instrument, knitting, crocheting, carving, kneading bread dough...anything that allows you to use your hands and wrists is that such activities tend to help maintain and improve both mobility and strength, thereby reducing overall pain.

You might want to look into:
*Use of heat and arnica gel to increase mobility before/after playing
*Warm-up exercises aimed specifically at the arthritis
*Strengthening and stretching exercises
*Wearing elastic "sleeves"/fingerless gloves made to hold body heat around the painful wrist/hand areas.
*Work with someone (like Ron Pinkham at Woodsound) to find
      technique changes for better use of your available mobility
*Appropriate wrist braces, usually used at night
*Trying different instruments and different techniques
      (smaller, lower action, electric, mountain dulcimer,
      open tuning simple less stressful chords, etc.)
*Working with an arthritis specialist who also understands
      the needs of musicians.

If leaving guitar playing behind is your preferred choice, fair enough- yet do please find other ways to strengthen and use your hands and wrists.

Just one of many who care,
Maeve