I replied on the UC board, but on the offchance somebody might see this in the future, I'll repost my reply here. It's a bit long and rambling; I wrote it just before going to bed last night.
Yes, I had major issues adjusting. I had definite Crohn's, so the j-pouch was ruled out from the start - however, my surgeon left the rectum in, thus leaving the possibility of an ileorectal anastomosis. (ileum-rectum connection). But like you, I also had to treat it as though the ileostomy could have been permanent.
I didn't cope with it well, at least for the first year and a half (had the stoma for 2.5 years in total). However, a couple of things made it considerably harder for me: first, I'm autistic, so I'm already highly resistant to change; second, I was traumatised from years of illness & pain, emotionally abusive parents (who I was living with, making it a million times more difficult), and difficult withdrawals from oxycodone and prednisone (particularly the oxy! Wasn't even on it for very long, but I developed excruciatingly sensitive skin as a result).
I complained an awful lot about the stoma on the UC and Ostomy boards in 2013/14. I was envious that I couldn't have a j-pouch and couldn't accept my stoma. I also had regular panic attacks about supplies - mostly running out of them, particularly after the zombie apocalypse.
The good news is that after about two years - probably a bit less in fact - I had become fully acclimatised to my stoma, physically and mentally. For the first year, I was dealing with leaks, bag filling with gas during the night, trying out different bags, etc. Eventually all those teething problems were sorted out - leaks became a thing of the past, I had found a setup that I was happy to stick with permanently, and I could sleep throughout the night every night without needing to get up to empty the bag. Mentally as well, I had adapted: the stoma had changed, without me even noticing, from something I regarded with disgust to a neutral body part.
You might wonder why I went on to have a reversal then; I wonder that too to be quite honest. The answer is pretty simple though; I had a reversal because I could - after a couple of years had passed, my surgeon was happy to do it (she wouldn't consider a reversal during the first year). Whilst I would be lying if I said I missed the stoma, I most certainly do miss not being on any Crohn's meds, being able to eat a wider variety of foods, having less pain, etc.
Anyway, I do think that if somebody like me could get used to living with a stoma, then literally anyone can. People's experiences vary wildly - I've known some people on here accept their stoma straight away. According to my stoma nurse, it takes about a year on average to get used to having a stoma. Apparently those who have elective surgery adapt faster than those who don't. I don't think that was true of me though; I kept on regretting my decision to have surgery, which was stupid - it was only elective because I was on high dose steroids. Would have been in your boat if the steroids didn't keep me afloat - they didn't heal my colon by an iota, though, that was the funny thing.
Apologies for rambling, but hope you can find something useful/comforting to take away from this post. I do recommend counselling if you can get it.