BAIL!

That is all.

"confirmation bias- Every time he says or does something that's disrespectful and/or out of line it justifies me being pissed off at him and also somewhat at his Mom"

Ugh, this is a very hard thing to conquer.  I feel the same way about my skids.. .sometimes I even go looking for shit, for confirmation that I am right about them being shitty people.  I think it's because I feel guilt for not liking them.  Like I am the type of person who gets along with EVERYONE!  I really don't have anyone that I don't get along with and the couple of people that I have come across in my 47 years that I just don't care for, I just stear clear of. Unfortuanately skids (and BMs) are in your face.  You can't always stear clear of them!  BUT I did try!  I went into the relationship with DH thinking that I could be friendly with BMs, that we could all sit together and chat at soccer games and birthday parties.  And I thought that I could treat skids like my own and we'd live the Brady Bunch life.  Yeah, that was an epic fail, but again, not for my lack of trying.

I really don't have any advice, I guess I can just tell you I understand and know how much it sucks.

Really makes me want chips. You're not married, don't have kids together, lucky you. You and your child can easily leave, and it would be better for everyone. She needs to focus on her parenting skills anyway.

I agree with others to get your DD out of there.

I went thru this type of thing with SS18.  The skids were taken from BM in 2010.  AFter 2 years, things were getting really bad with SS and his violence...getting kicked out of school every week, trying to bust holes in walls and bust out windows.  I finally had to tell DSO that either he had to get his own place to get SS out of my house or SS had to go back and live with BM, I wasn't backing down on it.   

AFter 6 months at BMs, SS was arrested and spent 3 years in group homes and juvie bc of his violence.  AFter those 3 years, he was still having melt downs and BM was calling DSO every week about SS because she wanted SS to live with us.  When the court said SS had to live with DSO, I said that I would move out until DSO could afford his own place, he had SD at the time too.   SS didn't want to live with DSO, so that ended well.

I didn't have kids at home but I have a gson who is 3 years younger than SS and I was afraid to have them at the house at the same time.  I was afraid what SS would do at nite when I wasn't around to hear if SS was hurting or abusing gson.

This kid is 17 and almost having a meltdown over CHIPS? WTF?

In my opinion, mom is nitpicking him. He’s a teen and there’s plenty she can ride him for but bringing home chips? That were given to him because they were nearly expired? What is the big deal? She needs to learn to pick her battles and who knows maybe the household will get a little quieter for you all. 

Wonder if the chips were stale....that is pretty pathetic to get that pi$$ed about stale outdated chips....You might want to consider a really long walk, and take your suitcase.....(and your DD)

It's clear you're a thinking person if you considered the role of confirmation bias. I agree a bag of chips seems like a small battle to wage. But your SO waged it for some reason so maybe you need to talk with her about peace for all of you being more important than a bag of chips. Step lightly -- no one likes being told they're parenting the wrong way. Maybe SS really did think he was doing something helpful if that's what he said. It might be nice for SO to see you're willing to give him a break on the chips thing. SS is at a difficult age for all kids, so best to only fight meaningful battles.