Why does Leonie treat her kids so poorly in Sing, Unburied, Sing?

Leonie has led a pretty troubled life, to say the least, and she passes her troubles on to her children. Thanks to the baneful influence of her husband, Michael, she started doing drugs, a nasty habit that only intensified when Michael was sent to prison. Yet despite the negative impact that Michael has had upon her life, Leonie still loves him dearly. In turn, this creates problems in her relationships with her children, as it seems to be the case that her love for Michael involves neglecting her parental responsibilities.
Furthermore, Leonie's trying to deal with traumas from her past, such as the murder of her brother Given, who appears to her in spirit form when she gets high on drugs. Leonie also finds it incredibly hard to deal with the systemic racial prejudice of the time and place in which she lives. All these factors combined make it difficult for Leonie to be anything like a perfect mother.