Expectations. The mother put too much expectation on the child it became a 'curse' that binds them.
I think it's more in the line of emotional abuse. There are two lines I could pull out from that mess, "うるさい (urusai)" and "いらない子 (iranaishi)", the first one I recognize as something along the line of "shut up", and running the second one through an online translator gives a result along the lines of "unwanted child".
But my knowledge of Japanese is very limited, so I could be wrong (and online translators are... unreliable).
