First of all... you are not acting like a child. You are acting like someone frustrated and angry with having even more heaped on top of what you've already been through. Insomnia sucks. I've dealt with it on and off for a long time. I don't have a magic answer for you, but listening to your therapist seems like a good idea. I know it's easier said than done. What you are going through is exhausting enough without heaping the sleep deprivation on top as well.
This is the depression talking. Your loved ones and supporters do not think this, let alone say it.
You will get through this. Whether it's tomorrow, next week, next month, next year.... you will persevere. You have such an incredible fighting spirit. I admire your courage in sharing your journey. I wish I could do more for you, but I hope my words of encouragement help.