I can also relate to depression and what others have said so far. I've struggled with depression and anxiety (panic attacks) for years (ever since middle school) and, even though I'm taking Prozac, I still struggle with it. Don't get me wrong, as Prozac has helped me tremendously over the years; it just doesn't solve everything. It mainly just takes the edge off.
This fissure has brought back a lot of depression for me. Even though I'm currently healing and doing much better than I was a few months back, I get very depressed and anxious. I'm constantly worrying if the fissure will re-open and come back. It scares the heck out of me. I'm constantly worrying about what I eat and how my BMs will be. I worry if I will someday need surgery, which terrifies me. I'm tired of living in fear. It's very exhausting. : (
So just know that you are not alone. What helps me is getting my mind off of it (I do this by enjoying my various hobbies, including photography and video gaming). I also try to go out with friends as much as I can (as long as I'm feeling up to it) and take day-trips in the area. Sitting around the house all day, every day just makes me worse and causes me to ruminate on things. If I'm having a really bad (painful) day, I will stay home and try to relax. Talking to someone you trust (for me, it's my mom) also helps a lot. There will be days where I cry a lot, too, especially if I'm having more pain than usual. It helps to let it all out sometimes. Otherwise, it just festers inside you.
Have faith in your body and know that you are healing. This, too, shall pass. That's what I keep telling myself every day. One day at a time. You are healing.
Best wishes to you. : )