If you are not going to do anything about them and if they are just "general" thoughts (no plan) then call their bluff? When I use to think about "suicide" it sometimes felt nice because there really isn't any "bottom" that can be deeper/worse? Such thoughts had a steadying influence on me and "kept" me from thinking about my actual, real problems of the moment that were confusing or which I didn't think I had any control over or way forward. Think of the suicidal thoughts as a "brick wall" and picture a brick wall and then over time maybe build yourself a nice "walled garden" and stick a gate in it and walk out occasionally?

I was once doing a guided imagery thingy from a book I think and pictured my "safe" place and it was/is a library/computer/office sort of place, kind of like Henry Higgins' rooms in My Fair Lady? Anyway, I have French doors that go out into such a walled garden where there is an apple tree and nice flowers and a bit of lush lawn, cool breezes, etc. But I capped off the whole thing by going to an antique store and finding a brass house key from the 1800's, a lovely, simple key, and I put that on my actual keyring. Now, when I get discouraged or unhappy I can "handle" and look at this little reminder of a pleasant, relaxing place and think of things I might like to do if such a place existed and then try to recreate them in some way here. I'll read a favorite book or something with an author good at description and revel in the relaxation/distraction I get from my problems for a bit there.

Perhaps the most useful, wisest thing my T said in 18 years of therapy with her was, "just keep putting one foot in front of the other." That she said that to me and that I can remember the incident calls her up and I'm comforted by how we worked together and she understands/understood so I don't feel quite as lonely, even putting that dreary-sounding advice into action.