Breastfeeding while smoking weed, etc?

This may be a little long apologizing in advance! My boyfriends brother had a kid with this girl, and we are the baby's godparents. well she is breastfeeding and I'm all for breastfeeding but she is smoking weed, drinking and not pumping and dumping, and currently is on percucet all while still breastfeeding!! She had nerve to say her breast milk is filtered really well that she knows the baby is not getting any of these harmful things, sorry but I'm pretty sure breast milk does not filter itself! I do not agree with her doing all of this but I feel like I can't tell her how to raise her child, I mean the baby is my godchild but she's not my child to say what she can and can't do! I just would like some feed back on what other moms think about this