It sounds like you're describing two attitudes towards immortality, an abstract one and a concrete one. The concrete attitude: "I don't desire never to die, but rather not to crumble away into something just more than nothing." "What's more likely in any given ten year period, pristine immortality being fully resolved, or somebody awakening my mind to an existence I would never want?" "The opportunity for suicide does not alleviate these issues, incidentally, because of my certainty I would not choose it." I will not comment on these concerns today.

The abstract attitude is summed up by:

I believe that death as a horizon event is necessary to my sanity.

The map-territory distinction is useful here. You should say instead

I believe that "death as a horizon event" is necessary to my sanity.

The idea of death allays your anxieties by inspiring healthy emotions. That doesn't mean that the idea of death should inform your decisions. It's possible to comfort yourself with the thought of death and then go ahead and sign up for cryonics anyways, just like how people can comfort themselves by not thinking about death and then go ahead and wear a seat belt. But you no doubt have other, more concrete objections to cryonics, which takes us back to your first attitude. Those objections are better reasons to make "deathist" decisions.

Better yet, you could use a different narrative to comfort yourself. Just because the thought that you're going to die someday succeeded in allaying your anxieties doesn't mean it's the only narrative that can do so. (That it is sufficient for your sanity does not imply that it is necessary for your sanity!) It's worth spending some time on looking for an alternative narrative that's just as comforting and which is more concordant with your preference "not to die tomorrow".

If you do switch narratives, you might find that you're no longer "deathist" but none of your decisions have changed. In that case all that changed was your aesthetic. But I suspect if you change your abstract attitude towards death, you might find that your concrete attitude changes as well: You might notice ideas you didn't notice before, which make important life decisions more or less compelling.