Ah, but what are the chances of your cancer coming back AND getting hit by the bus? LOL...
Something to remember: a positive attitude does NOT improve cancer outcome. That's a load of c**p. There are studies to disprove this irritating theory. Irritating because you have to deal with people telling you not to dwell on the negative stuff or you'll have a bad outcome - how can you ignore it, huh? Let me know if you figure that one out.
Don't blame yourself for the smoking etc. Cancer happens, often for no reason. People are always trying to figure out why they got cancer, and do a "if only I had (pick one) eaten vegan, exercised more, etc. I wouldn't have had cancer" story. I've seen very healthy-lifestyle people get it. Ho hum. You had a life. Cancer isn't the punishment - it's just very bad luck.
You are lucky - it sounds like you still have all of your tongue in working order? If not let me know. Sorry to be so graphic but that was undoubtedly one of the possible outcomes.
Are you really okay with going back to work at all? Is it adding to the stress? If you have ongoing pain from the radiation (not unusual), and need narcotics to manage it, you might consider SS Disability.
You're bound to feel different now, about work and life and pretty much everything. You've had an encounter withe your own mortality and it's pretty scary. Also, for quite a while you were out of work and now you are back on someone else's schedule... it's different.
And for me, work seemed so trivial with my fear about how long I would live. I was almost 48 when diagnosed; I've managed to work until now (almost 62). But I really don't care about work any more. It's just a way to make money and so on. I sort of compartmentalized work and reality into two separate sections - on the job I ignored the cancer fear; off the job not so much.
So anyhow... call the oncologist, ask them what therapists work with cancer patients frequently or if there's a GOOD group out there, do all that stuff to get your head straight. You're dealing with a major stressor and oddly enough, when you finish treatment it often hits you hardest: you no longer have those regular appointments with the docs and you're on your own. This happens a lot.
Sorry for the rambling... but oh well, it's Monday morning I'm at work and wish I wasn't!