I really need some advice/help at this point. My anxiety is really bad because I haven't slept well in two weeks. It started with one night of very bad sleep and just escalated from there because I started having a lot of anxiety about sleep

Last week I slept poorly almost every night and averaged out at around 5 hours per night. This week has been even worse. I have not gotten more than 4 hours a night so far!! I've had to miss some work this week out of sheer exhaustion and I've never been so tired or felt so out of it in my life. I want so badly to sleep, probably more badly than I've ever wanted anything. I feel so miserable and this lack of sleep has already caused bad depression. I am not excited about anything, dreading the future, and I cry multiple times per day almost uncontrollably. My life feels so out of control since this has started.
Additionally, I take .5 mg lorazepam every night now and am terrified I will become addicted. If I don't take it, I don't sleep at all. Usually after I take it I get about 3-4 hours and that's it for the night. I feel a strong desire to then take a second .5 tablet to get another 3-4 hours and therefore get a healthy night's sleep but have been avoiding it due to fears of addiction or dependence. I have seen a couple doctors about this and they don't want me to take more than .5 mg, nor do they think a strong sleeping aid such as Ambien would be right for me. They want me to take Zoloft, but it has the downside of causing initial insomnia. I also currently take melatonin before bedtime which has a mildly calming effect but has never been enough to get me to sleep.
My specific worries are: That I will have some sort of physical or mental breakdown, start hallucinating or hearing voices, have to miss more work and lose my job, be unable to perform in a concert next week that I was scheduled for, become dependent on lorazepam, that the lorazepam will stop working, that I will literally become too tired to function, and even that I will die from lack of sleep. Sorry for the drama but I truly do feel like death and can barely focus or make it through the day. And when my head hits the pillow at night, I am for some reason wide awake. It's terrible. Since I have always been almost physically incapable of taking a nap, it is very hard to get through the day.

Does anyone have any advice or ways I can combat these worries? Has anyone else struggled with insomnia and care to empathize? Hearing others stories would also make me feel a lot better I think. Also for real though, how long can one run on 3-4 hours of sleep per night before something terrible happens???