Oh that song. Ugh. Am I the only person who liked the movie but thought it should not ever be compared to the masterpiece that is the Lion King? And now that song, which I do not like, is stuck in my head! heehee..
Therapy. That's how to let go.
Actually, letting go takes time and, I agree with Kitchensqueen, the acceptance and understanding that you cannot change other people, nor can you change something that has already happened. I practice mindfulness and being in the present moment. Maybe it sounds cheesy but, if I feel sad I will think "I'm feeling really upset right now. Given what has happened, this is a totally normal feeling. Like all feelings, it will pass." then I let myself be sad- I cry, I reminisce about the past, etc.. and I mentally watch that feeling, I guess, float away from me. I don't know if I sound like a weirdo- but sometimes I actually visualize the feeling and watch it slowly dissipate as a cloud floating away from me. The more I think about an emotion as being impermanent, the easier it is to be present with that emotion and then let it go. Things that were really REALLY painful years ago, have become easier with time because of this.. and with CBT. I do have some triggers that I avoid and sometimes I am derailed by unexpected events or triggers but that's where cognitive behavioral therapy has helped and I do allow myself to feel those feelings caused by the trigger without pushing them down or clinging to them.
If the sadness permeates me at an inopportune time, I put it away for later. By giving myself permission to be sad later, I can enjoy the kids or the activity I am doing at that time. It's taken practice, and it's tough to do sometimes, but that also works so I don't dwell on things. Dwelling on things is a form of clinging and it's been really important for myself personally, to be able to let things go. Really crappy stuff has happened to our family and repressing it/acting like nothing happened or dwelling on it would not be a healthy way to raise children or keep myself healthy. It was essential to find a healthy way to cope for my own sanity. Good luck!