Looking for a doujin about a school girl who gets kicked out by her parents and ends up living with her teacher who fucks her, her friend tries to save her but ends up getting fucked as well. Pretty sure one of the ending pages is of 2 boys in a store and they walk past a porn video of the 2 girls.
They might have had also been drugs or them wearing a collar just in case that makes it easier to find with tags.