I'm in exactly the same position OP with DS2 (26), i know how truly horrendous and terrifying it is!
I will say, 2 of DS2s best friends took their own lives in 2022, and i think one of the crucial factors was that they didnt have good relationships with their parents, or mates to talk to, so were largely alone.
Your son isn't, he has you and good friends.
Also my son HAS now suffered (3 weeks ago) his 2nd girlfriend who he lives with, suddenly deciding over a weekend, that she doesnt want to be in a relationship anymore.
We did have to do a dash down the motorway to collect him, with our phones in hands and DS1 constantly ringing for an update.. but i'll say this time, although we were so scared again, he seems slightly better at handling it. At least he wasn't rolled up in a ball on the floor clutching his head and rocking this time..
DS2 had a lot of counselling in between girlfriend 1 and 2, and i think its really helped, along with learning and carrying out relaxation techniques every morning before work (also in a stressful job). Is that something your DS might consider for when he comes off his Anti depressants?
I know how terrifying and stressful it is for you, i know what its like not to be able to sleep, how all consuming the worry is, and how easy it is to panic about it happening again, but it really might be easier for your DS to handle if he does get hurt again, they're a little older and wiser.. also is the situation something the two of you can have a talk about i wonder?
Meanwhile it really might be helpful if you did tell a member of the family that you're close to, or find a good private counsellor to offload to, if you can afford it? x