Why am I feeling so triggered by this?

[3isthemagicnumber]

A year ago this weekend ,we returned from a bonfire party to find our eldest ds,then 15, had attempted suicide .As you can imagine ,the devestation was indescribable .
A year on,whilst he is not entirely 'well' ,he is most definitely living life and now has lots of support and tools -medication ,therapies ,support,awareness of his MH condition etc so you could argue that he is obviously in a much better place than he was a year ago due to those factors ,so why am I feeling so scared again ?
DH feels if anything we should feel almost celebratory -a year has passed and we ,and most importantly ds ,have survived but I can't feel that way .I feel more worried than I did ,say,3 months ago yet he is 3 months further down the line if that makes sense .
I can't shake this feeling of doom and the fireworks and invites of parties etc just make me want to hide away .
How do I turn this around ?
Ds himself is being quite nonchalant about it and unsurprisingly doesn't want to talk about it at all .However ,I'm worried about that too -that maybe he is burying things again .He ,again probably understandably ,gets defensive and annoyed if I ask him if he's alright at any time ,not just now .I don't want to be making a big deal about it ,so in front of ds I'm not at all ,but should we ? Should we be saying -wow ,look where you've got too etc (we have and are forever telling him how proud we are of what he has achieved ) or should I just not mention the significance of the weekend and just treat it as normal? (or our new normal ,as it has become ) .

I wouldn't make a big deal about the anniversary - I think anniversaries can be really unhelpful. Don't bring it up unless he does. Also, a year isn't long. It's been two and a half years since my DD took an overdose and looking back, although she self harmed after that, she didn't attempt suicide again but it was constantly on my mind for two years. To begin with I'd wake every morning wondering if she was alive. Then gradually it got a bit better but every time she was late home, every time she was in a bad mood, I'd worried myself sick. I've finally begun to relax in the last six months but even now, if I come home and she's not here when I was expecting her to be in I can feel dreadful. I think maybe I'll never be able to completely relax again which is crazy because she's really not at all suicidal any more and hasn't been for a very long time. It's just something I have to accept and, as I say, it's been much better in the last six months. If you're sure (as sure as you can be) that he's doing OK and that your fear isn't a sixth sense telling you something's wrong then just keep reminding yourself that it's normal to be worried but try not to let him see it.