U could try taking a teaspoon of apple cidar vinegar each and every morning, which is what I do to rid myself of heartburn. Heartburn (or stomach acidity) is caused by not getting enough acid in your body, thus the stomach produces more acid then it should. If you take something that gives your body some acid, then your stomach will cease from creating it instead. Apple cidar vinegar by Bragg's seems to be the best, and highly recommended for this situation. Then, you could drink as much coffee as you'd like. Hope this helps.
You could also try some Gano Excel coffee, as this seems to be the healthier choice for coffee, even though those who are stuck on the coffee bean would prefer that as thier choice of coffee! I'm a health advocate, and highly believe that one should take a healthier approach to life's ailments.
I used to take tums many years back, but found myself having to take one almost every hour to rid myself of the pain. Switching to apple cidar vinegar has helped me where I only take, at most, one teaspoon every morning. I can sometimes go days without needing another teaspoon!
Hope this helps!