An addiction to alcohol.
I'm trapped in my glass prison, can't break out all alone.
Glass Prison can refer to a few things. Generally it is used to describe an addiciton to alcohol. However, it can also be used in the context of emotional problems. By having a mental problem that nobody can see, one feels essentially trapped in an invisible box. A 'glass prison' of such.
"I cannot break out of my glass prison all alone"