Hi Lisa,
I'm so sorry to hear you're going through a bad time. Sjogren's syndrome (SS) affects everyone in different ways, but many of us go through a series of flare-ups and remissions. So you won't necessarily always feel the way you do now.
Concerning the TMJ, as far as I know this is not SS related. There are many causes, and the solution depends on the cause. You really need to see a maxillofacial surgeon about this. They are the experts. (Don't be put off by the word "surgeon" - most of the solutions are not surgical.)
The sicca symptoms and Raynaud's are, of course, down to SS. Raynaud's is made worse by the nicotine in cigarettes, but it's by no means an exclusively smoking-related condition. I have it too and I've never smoked in my life! Mine suddenly started at age 60, ten years after I had my first SS symptoms. In fact, the appearance of Raynaud's was instrumental in my doctor finally making a diagnosis of SS. In the ten yeas up till then my GP, a couple of dentists and an ophthalmologist had been putting it down to allergy, old age(!) and goodness knows what else. You're actually quite lucky to have got a diagnosis so quickly. Ten years seems to be about par for the course, going from what many posters on here have said.
I'm sure no one is going to judge you for smoking. However, smoking conventional cigarettes is definitely going to make the sicca symptoms worse, especially the dry mouth. SS can also affect your lungs as it progresses, so you might want to re-think the decision to continue on this basis too. I suddenly started developing asthma at age 70, and my doctor warned me that I was developing the very early signs of COPD, in spite of never having smoked a single cigarette in my life. Fortunately, use of a low-dose steroid inhaler has now brought this under control.
Why not try gradually phasing out cigarettes in favour of vaping? This won't help the Raynaud's, as it's the nicotine that causes that. However, it's the tars in conventional cigarettes that cause all the lung problems, as well as cancers in other parts of the body. Vaping wouldn't have nearly the same effect on your sicca symptoms as cigarette smoking.
I volunteer in a mental health centre, and I was having a conversation about vaping only the other day with a young man with severe mental health problems - a group where heavy smoking is quite common. He had been on 50 a day since his early teens, and it had already started taking a toll of his physical health by age 30. He was really singing the praises of vaping. His terrible "smoker's cough" (which is also due to the tars, not the nicotine) had disappeared, and he was delighted at being able to run up flights of stairs again without getting breathless.
However, there was one thing he said that really caught my attention. He said his nicotine consumption had also gone down since he'd started vaping. It seems that since he's had his e-cigarette, he actually smokes for shorter periods. He said that most smokers don't like to waste a normal cigarette, so will smoke it to right to the end, regardless of whether they really want it all or not. Since he's been vaping, he's noticed that he just pulls on his e-cigarette till he feels he's had a sufficient nicotine hit, then turns it off. He's also noticed the financial effect of this!
So... stop beating yourself up about smoking, but try to replace at least some of your daily cigarettes with vaping. See a maxfax about your TMJ (which may well be causing your tinnitus as well). Take your rheumatologist's advice about your sicca symptoms. And keep hanging out on this forum, where you'll get all kinds of support and useful advice from fellow sufferers.
This site also has a number of forums on oral and dental problems, where TMJ and its treatments is often discussed. I know this because I went on there when I wanted some input on a dental problem (not TMJ) that I was having last year. They may also have a specific TMJ board.
Try and stay as positive as you can. Some of us find this has a big effect on our SS symptoms.