Moral dilemma

Idk who else to ask so here I am....

I have chance to help out a child but it would impose upon my own family’s lives greatly. I feel obligated to help out because as inconvenient as it may be I could make it work.

Details...

My cousins daughter has no where to go after school she is 14 and has struggled with self harm n suicidal thoughts. My cousin is terrible mother FYI n kinda crappy human. Sorry not sorry. Her daughters had to find places to stay after school for past week since her bio dad works late and can’t get her (also a POS this poor child) I could drive the half hour to get her from school by 3 and get home by 4 to get my older two off bus (7 &6yrs old) but I’d also have to load up my 17month old and 1 1/2week old baby to do so. I’m in pain n still healing from just giving birth and honestly don’t think I can handle adding another kid to be responsible for right now. Plus another mouth to feed and gas to go back n forth Mon-fri.

Am I being terrible for not wanting to. If I had to I could suck it up n force myself. Any thoughts at all appreciated