Whoa! You have a lot going on at the same time. I would suggest you eat what sounds good to you. If you eat an apple, add some cheese with it or peanut butter. I live alone and often grab pieces of meals to make up something healthy. Maybe some tuna salad on green salad? Mix some spinach into pasta sauce with lots of parm?
Speaking of smoking, I quit smoking in ~2009, I think. It wasn't that monumental for me--I just got sick of it. I had smoked for about 10 years on and off after I divorced. The 90s were all about happy hours and parties (I was in my 30s). I smoked cloves which, omg, I loved! [As an aside, this was when the Atkin's diet was big and I thought it was insane to eliminate food groups, and eat so much fat and meat, so I to make my point, I would tell people that I was on the "diet that ends in i" like martinis, calamari, cannelloni, etc. because it made about as much sense to me as Atkins].
When Obama made flavored cigs illegal, getting cloves became a big deal, so eh, I decided it was time quit because I wasn't really smoking
that much anyway. Well, holy hell, did I have withdrawal not because I wanted a cigarette but because of the brain chemicals! I was a cast-iron bitch on wheels--so much so my boss called me in her office and suggested therapy.

I gotta say that did not go over well with me but it sealed the deal that I would
never pick up another smoke again if going through withdrawal would jeopardize my job! After I left her office, I googled withdrawal symptoms and, whew, I could at least attribute my attitude to a lack of nicotine. I went into her office and explained what the problem was and she too was relieved there was a good answer. Geez...that still stings.
My point of that trip down memory lane is that you have a lot going on now, and after your surgery, your hormones will be whacked for a while. There will be challenges coming from everywhere. So--
give yourself a break and just do your best. A lot of the drama is out of your control and all you can do is focus on your goals. We're here for you.
