Coffee and sweetner
I used to buy a "Grande" coffee at Starbucks and put 12 packets of sugar in it. TWELVE. Prior to surgery my doctor had me "kick" caffeine and sugar cold turkey. On those days I felt "faint", for at least a week. My surgeon says no caffeine, as it can contribute to ulcers. So, since I know and knew that I had a big sugar problem, I decided to just never use sugar anymore, and to try to avoid having my tastebuds re-adjust to that "sweet taste". I use 1 and 1/2 packets of Splenda in my coffee these days. No sugar. Last week I was at a conference and there was no Splenda, only Equal. I have a problem with Equal as it causes me physical pain in my joints, and I really think it's poison. So instead of using the Equal, I used 3 packs of sugar. I actually felt pretty guilty about that, but I only drank about 1/4th of a small cup of coffee. I should have just had it with no sugar at all.
So, I drank about 2-3 cups of coffee everyday prior to surgery. They tried to tell me at my doctor's office that no more coffee after surgery. I finally made the Dietician admit that it wasn't really the case. They definitely don't want you near coffee in your first 6-8 weeks, so that I did follow. However, I did start back and on months 2-4 I was lucky if I had 2 cups of coffee a week. I did add my flavored creamers back in it, back would only drink a half cup at a time. However, during December I went home for Christmas Vacation and began to drink more Caramel Macchiatos and other coffee drinks 2-3 times a week. They were non-fat, but I hate the sugar-free taste and didn't switch out from the regular. Anyway, recently in the last two weeks I've had to cut those back out again as I felt my weight loss has slowed down a bit. Once again, the weight is beginning to come off again so either I was in a stall, or in a stall that the coffee drinks weren't helping.
So now, my strategy is maybe once a month to treat myself to a coffee drink. However, in the meantime stick to regular coffee with a bit of flavored creamer and only one cup per day, if that. I am trying to alternate it with herbal teas. So hard. I do understand that some people develop ulcers and I hope I won't be one of them. So far so good (knock on wood).
I have also resorted back to Americanos, since they are straight up expresso with ho****er. They get my caffeine kick in and are zero calories.
I stay away from sweetners, I've never like the aftertaste. If I have to use sugar, I prefer Raw Sugar. Fortunately, I don't dump. But I rarely if ever add sugar to anything anyway.

As far as SHOULD you drink coffee??? Well.. That's a choice only you can make. My program ( which is overseen by Seventh Day Adventist ) says NOOOOOO. I drink it.. I have a Click protein shake every day. I might have one cup of coffee every day or so.... Nothing like I used to drink lol.. I could easily go through a pot or two a day. I have had ulcers since my RNY but, I wasn't drinking coffee at that point so it didn't play a role in my getting them.
Personally my motto is all things in moderation.. If you want an occasional cup of coffee .. Enjoy it

I didn't drink coffee for the first 4 months. Instead I drank decaf tea with splenda. I have always used sweetner. At about 4 months I started drinking decaf coffee as an occasional treat. I added sugar free french vanilla coffee mate. Now at 20 months out I drink a cup of coffee every morning with theSF french vanilla creamer. I limit how much I drink because it still has calories even though it is SF.