Must I give away the money I took from my aunt that was from usury, given that I found out about it later and that my financial situation is not easy now?

If you were unaware of the money's prohibition, then there is no sin upon you. You are not required to compensate for what you took. However, you must inform the owner of the money that illicit gains must be disposed of for the benefit of Muslims or given to the poor and needy. It is not permissible to spend it on anything else. If a poor person takes it, it becomes permissible for them.