I am struggling with guilt, anger, sadness
Pretty much every parent who has had a kid dx'd as T1 has experienced that.
My parents are in their late 70s, I've been T1 for 29 years now, I'm pretty comfortable with it, it doesn't bother me that much (having a libre sensor stuck on my arm so I can be pro-active with shifting levels helps a lot) but when I take them out for lunch my mum usually mentions at some point that she still feels a bit of guilt about how she sent her laddy off to university and he came back diabetic!
It's maybe just an inate part of parenthood - that overwhelming urge to look after kids that parents automatically blame themselves if anything goes wrong, why wasn't I there, did I feed them the wrong thing, what could I have done different.
I made the mistake once of telling my mum that it's a totally random, luck of the draw thing which maybe has a genetic component to it. Boy, was that a mistake - genes?, she said, so then she's worrying she'd passed on duff genes! Although I think it was just a ruse so I'd be compelled to buy her another Baileys to calm her down!
My take on it is that as a parent you will probably carry on blaming yourself at a subconscious level because that's what parents do, even though at a conscious level you know that it is a random condition which can happen to anyone regardless if upbringing.
You can rest assured that although it isn't a walk in the park, and there will be some messy hypos along the way, lots of us go on to live full active lifes and just have to plan ahead a bit more than your average guy. When I was jumping on a plane to go backpacking for six months, my parents were more worried about it than I was - I had the time of my life!
Don't wrap him in cotton wool. Sure, you and his DSN will be on hand to guide him through the basics of how much insulin for each meal and keeping an eye open for hypos, but he's at an age where it will serve his interests in the longer term to be engaged in the decision making processes and think about, ok, this meal is x carbs, so how much insulin does that need?
Mistakes will happen. There's a large degree of randomness in T1 which confounds even old timers - we never get it right all the time. So don't think of going out of range from time to time as a failure - it will happen despite best efforts - but more of a learning experience: why did that happen and what might I do differently the next time?
Read the book Breakthrough by Thea Cooper about the discovery of insulin. Motivational piece in it quoting a letter from Elizabeth Hughes, one of the first kids on insulin, to her parents, telling them how she is going to be, "captain of my own ship", by dispensing with nursey and taking her own injections in days when the syringes had to be boiled and the needles manually sharpened. Your boy will learn ingenuity, forethought and planning just like Elizabeth did.
Hypos are not nice. They're not painful (can't speak for everyone, but I think it's generally the case), it's more the confusion of thought. So don't go firing endless questions at him about are you ok yet. It can be difficult articulating answers when hypo and people quizzing you or being too in your face just adds to the stress. Although they can be distressing, both for the T1 and onlookers, the good news is that most hypos are sorted out very quickly with modest amounts of glucose. There's a very fine line between blood sugar being just right and too low. Most common or garden mild hypos can be sorted with 10 or 15 grams of glucose. Many people way overtreat, because they just eat till they feel better without realising that even neat glucose takes several minutes to get from the stomach into the blood stream, so they end up too high, so then end up on a rollercoaster taking more insulin to bring it back down. So, generally 10 to 15g, wait 10 to 15 minutes, rinse and repeat if not better. Amounts will need adjusting for more severe hypos.
The other big thing to watch out for is burnout. Some people take it very seriously after dx, then in their teens ignore it and run around with sugars in the high teens and 20s for extended periods. They feel fine, don't have hypos, think they are bullet proof, but it massively raises the chances of developing serious complications which can build up pretty quickly in the background. It's fairly common for teens to go through a phase like that only to be pulled up sharpish when they're told they're developing eye damage. There's no easy answer to it, but keep an eye open for any clues that he's deciding not to bother with insulin that much.
Anyway, there are downsides, but a bit of common sense deals with most of it, and he'll be jumping on a plane to go backpacking before you know it!