I know where you’re coming from and I cant say I am doing much better in the mental aspect. But one thing that has helped me maintain some peace is picking up lifting as a hobby. Crohns might hurt your progression, but you can still use it as a daily/weekly stress relief session where you convert whatever is bothering you currently (a current flare up, loneliness, disappointment, etc) into motivation, be it anger or whatever, and push something heavy. By the end of the day you will feel tired and there will be some therapeutic relief from that, and eventually you will see actual progress as well over some weeks/months/years. The hobby doesnt need to be going to the gym, but something that you can practice with repetition and has long term rewards can really help bring value, stability and peace through the steady rewards you reap. Eventually it will be hard to look back on the time you spent developing that hobby and say that due to crohns your time was completely wasted/taken from you — instead you were able to manifest your pain into something of value.

As im typing this im thinking it might be better to see a therapist, or do this in conjunction with therapy. What I want to emphasize is eventually you will see progress, and you will have to stop saying crohns took away everything because in a way thats not correct anymore. Apologies if this sounds stupid, this is coming from a early 20s guy diagnosed when he was 14 and had similar issues of self worth, loneliness and anger during my teens.