A burglar gets revenge on drug dealers for past addictions keeping it secret from his D.A. brother; however after his brother’s daughter dies he has psychotic hallucinations that push him into suicidal undertakings as a vigilante.

The first half of the logline seams unrelated to the plot and can be taken out of the logline.

If the story starts after the niece dies then that is the inciting incident and should be at the start of the logline. Problem is there is no clear goal specified, what is it the MC must achieve or else?

Also I don't understand how the death of his niece would cause him to experience "...psychotic hallucinations?" and further to that how "...psychotic hallucinations?" wold necessarily cause him into being a vigilante. What is the direct cause and effect that makes one happen as a result of the other?

Lastly if he is a hallucinating, psychotic, vigilante with suicidal tendencies I find it hard to empathise with him and want to see him succeed. He sounds F'ed up and in need of help sure but certainly not a hero worth rooting for.

Hope this helps.