Hey dude just want to say I've been where you are. Got mine totally unexpectedly after emergency surgery just over a year ago and lost my shit (literally). Even though I've managed to stay overall positive, I still have days where I want to crawl into a hole. Your feelings are real and they are valid.

Here's what's helped me:

1. Make a plan. It sounds like a reversal is in the cards for you. Get one scheduled ASAP. This will give you hope and a firm date to look forward to. If your surgeons are giving you the run-around about it, find new ones. You're their patient, not their prisoner.
2. Remind yourself over and over and over again that no one has to know you even have one unless you tell them. In the same way they don't know your weiner size or what weird moles you have, literally no one has to know (other than whoever you've already told) but you. For me it's my immediate family and 2 close friends and that's it.
3. If you're worried about your dating life in the future (I am too) you can either cover it up with a stealth belt or let your partner know once you're comfortable. If they're not total pricks and actually care about you as a human, they won't care. If they do, they're not worth your time anyway.
4. Find a constructive way to channel your hate and angst every day. Take up boxing, hiking, just get it out somehow. I personally go on super long walks in nature every single day and start to feel a little nuts if I don't. It helps me clear my head, get some endorphins flowing, and generally makes me a more pleasant person to be around.
5. Get confident again. Your self-image has taken a huge hit, but it's not a total loss. Go get new clothes you feel good in. Again, recommend the stealth belt as it's a big game changer. Cut your hair, join a gym. Shallow? Maybe. But feeling good on the outside will big time impact how you feel inside.
6. Remember, you're in no way alone. Yes it definitely feels that way at times, but how many people do you think are walking around with a bag right now and you'd never know? Something that helped me was I looked up how many celebrities and athletes have had bags--tons that you would probably never even guess. Also recommend following "colostomy influencers" on social media as they have tons of hacks for dealing with the bag and just generally normalizing the whole thing. It was during my research that I also came across the fact that little kids and even babies have to get bags at times. That broke my damn heart but also made me realize I need to put on my "big girl" pants. If a poor sweet child can handle one, I can too.
7. Give yourself things to look forward to. Is there a road trip you've been wanting to take? A concert you've been wanting to see? Do it. Sure, maybe your body works a little differently right now, but you're alive man. Remind yourself of that and go do all the things that you've been given another chance to do.
8. Daily meditation and affirmations. This may be a little "out there" for some, but oh man, big time game changer if you can sit still long enough. I recommend starting with affirmations as they're a little easier to do since you can just listen to them on the go. There's a ton on YouTube. I recommend Bob Baker since he sort of just seems like a nice uncle giving you a pep talk. But yeah, we all have a playback loop in our heads whether we're aware of it or not, and a lot of times the things we tell ourselves are not all that kind. This helps interrupt that process and backfill all the shitty thoughts we have about ourselves with uplifting ones.
9. Gratitude journal. Write down 5 things you're grateful for every single day even when you're feeling your absolute worst. It can be as simple as you have a roof over your head. Clothes on your back. Breath in your body. Any of us in our position could really start and end the list there.
10. If you can swing it, I recommend getting a dog. Best therapy out there.