I am taking a course on quantum mechanics and I try to understand the time-independent Schrödinger-equation with the Delta-potential: $$\frac{-\hslash^2}{2m}\psi''(x)-V_0\delta(x)\psi(x)=E\psi(x)$$ where $V_0,m,\hslash>0$ and $\psi$ and $E$ are unknown. I can somehow mimic the procedure for solving the equation but I do not understand what I am doing there. The main problem is that I do not understand what $\delta(x)$ exactly means. I know that $\delta$ is a distribution which can for example be defined as being a functional or as being a measure. However, I don't understand why $\delta$ can take $x$ as an argument. I guess it is some abuse of notation, right? So, here are my questions:
What does $\delta(x)$ in the above equation mean? Or more general: What does $\delta(x)$ mean if it occurs in an ODE? How is a solution for such an ODE defined? If $\delta(x)$ is abuse of notation, what would be the correct notation for such an equation?
Of course, I know the "physicist's explanation" of $\delta(x)$ (i.e.: it can be used to describe a potential $V(x)=0$ for $x \neq 0$ and $V(0)=-\infty$). Unfortunately, this does not help me. I am looking for a mathematical precise explanation. A reference to a textbook would also be great (a mathematics book - not a physics book).
I've asked a related question on physics stackexchange. You can find the link in the comments.