Good night! 

I think I would have apologized to grandpa and freaking left. Never to be heard from again by this clan. 

This relationship is going to 100% destroy you and probably drive you insane. 

Leave this madness. 

Fire starters belong in Juvie. I'm absolutely serious. My mother worked with troubled children for years and they did not mess around with kids who started fires. And a 15 year old needs to be told not to start a fire? 

he only said “she mustn’t have heard us say no.”   And then he sat there like a mute.  ...

 his whole family plied me with wine and said how hard she is to deal with, how spineless he is, and they begged me to stay with him because he’ll be lost without me.  I basically had an emotional breakdown, and now here we are.  

You can't save this guy. He needs to save himself. Until he parents his child, until he gets her the help she needs (and a child who sets her grandparent's table on fire definitely needs help), you need to remove yourself from the whole situation. 

The only one you can save in this situation is yourself. Walk away.

Uh what!!! His family needs you to stay with him to keep him and his spawn out of their hair.  So what is so appealing about a grown man that accuses you of giving him and his kids lice after it's confirmed by the school his spawn did it?!? No man who humiliated me in that way would ever be graced with my presence again.  

and animal torturing...two signs of psychopathy.

Save yourself and RUNNN!!!!

No 15 year old needs to be told NOT to set a napkin on fire.

Your BF will put you in harms way to protect his daughter. He doesn't show respect to his own parents and their home, and they raised him. What hope do you have at being worth his respect when his OWN PARENTS aren't?

Cut ties with these psychos and move on. It's not worth it.

I agree with the other posters-your boyfriend is a horrible parent who is doing a major disservice to his daughter and everyone that will have to interact with her. His daughter is 15 not 5-she shouldn't need to be told it isn't a good idea to set a napkin on fire at a dinner table. She doesnt need to be told about "fire danger'-she set the napkin on fire to get a reaction. From your other posts, it doesn't seem like your boyfriend is giving you the respect you deserve.

I'm glad you don't live with this no back bone havin' man. Can you imagine the rest of his daughters teenage years......sure now she's starting fires, what will it be next?

Aint that much love in the world or good sex that could allow me to continue seeing this man.