I hear you! It's really hard to be able to open yourself up again after you've gone through a loss. I felt that way when my Frenzy died. She had a jaw abscess that spread to the bone and then causes probable sepsis... we tried so hard to save her, but didn't really know what we were doing (I was a fairly new owner and our vet at the time did not know as much about guinea pigs as he pretended to.) It was something I never wanted to go through again. We mainly got another pig because I didn't want Linney to be alone, even though I didn't really feel 'ready' to have another one, and I was always terrified about teeth issues after what happened to Frenzy. As it happens, a couple of years down the road Sundae (the pig we got after Frenzy passed) also developed a jaw abscess and dental issues, but with a new vet and more experience, we were able to get her through it, and I now have a more 'balanced' knowledge about tooth and jaw issues, and although I know there are always potential bad outcomes, I have a lot more confidence in my ability to handle them with future pigs.
As for bladder stones, I really don't know the prevalence. Pigs are prone to bladder issues, supposedly. Out of the pigs I've owned, one has a bladder stone and general bladder issues (Sundae again- she's my problem pig for health issues!) and two haven't. All were on the same diet, which my vet has said was a good one in terms of preventing bladder issues. I suspect there is some genetic component so it's kind of a toss-up.
((HUGS))- I'm so sorry for your loss. Emotionally it's so hard to have another pet when you are still grieving, and fearful of what could happen if you open up again to another animal. I think, in time, you'll know what to do. You may need some time yet to grieve and process.