Bless her, I can understand her feelings. I felt rough for a few days until it developed into intense pain and fever. My partner pretty much dragged me to the ER where they discovered burst intenstines due to diverticulitis; the surgeon said I had about 70% more infection throughout my system than he had ever seen before. My partner saved my life, as I was completely out of it and unaware of the passage of time. Of course, I, too, woke up with a colostomy.
Between the fever, the sickness, the op, and pain meds, I can't say I remember much...and what I do remember is confused with some hallucinations. The following months were surreal, two weeks in ICU, a month of recovery at home, back to work, back into the hospital for a reversal, another incident in hospital that resulted in a iliostomy, more recovery, finally a reversal of the iliosotmy, more recovery...and now back to my new "normal".
During all this, there was always something to be done; PT, learning to take care of my stoma, dealing with travel, getting back to work. But as I tried to return to a routine, I found myself uninterested in most things, constantly tired, and without motivation. In a word, depressed. Doing a little online research, I discovered that depression after major surgery is common. Anasthesia is essentially a controled, reversible coma; much like a reboot when they wake you up and it can cause some synapses in the brain to not refire in the same way for a while. Add to that the invasion to the body of surgery which is traumatizing, both physically and mentally. Then there's the pain and discomfort, a lack of mobility, and increased dependency on others. Quite a cocktail of issues to deal with!
Having a bit of your internal organs hanging out your side and having to deal with a bag full of excrement is bound to make anyone question their body image and self esteem. Even in the hospital, my partner would help me to the toilet; when I came home, he would empty my bag (he did draw the line at dealing with my surgical wounds, but I was fortunate to have a home wound nurse). One day early on, I just blurted out, "we're never going to have sex again, are we!" It took me months to even cuddle with him again, and that lack of touch when it has been so much a part of your life had to have contributed to my feelings of despair. Of course she's in a bad place, she's vulnerable, scared, and probably wonders (as we all have) if this will change people's attitudes toward her. And how she regards herself.
I approached it like an alcoholic: one day at a time. I will say that finding out that depression was to be expected improved my mental health as I learned it wasn't entirely my failing. It was also a great help to admit to my son and my partner that I felt depressed, so I could put my energies into overcoming it rather than hiding it with a brave face. Encourage her to talk and let her talk; everything doesn't have to relate to what you (or I) went through as her situation is unique.
You don't say what kind of insurance she has, or if she has insurance. With all that's on your sister and her husband's plate right now, perhaps you could call her insurance company and see if there's some home nursing included. Both times, my wound nurse helped and taught me about stoma care. Perhaps you could research services that would be able to offer an ostomy nurse, even if it's just an hour a week to help them with progress.
You could also order a range of samples in her name, to find out what products are most comfortable and efective for her. That way, you also get lots of sets of instructions to learn more. Ordering and aquiring supplies was stressful in the early days, fearful that I would run out! It's a worry you can bear for them.
Is her coloctomy reversible? That also impacts one's attitude toward it --- for better or worse.
I'll be a year since my emergency surgery on June 4; what a long, strange trip it's been!
And your sister is still at the beginning. Listen to her.
Love to you and wishes for the very best of luck along the way.