Boyfriend's brother finacee

Little back ground information I'm 18 years old but I live with my boyfriend(he's 18 also) because of the family issues I has before I turned 18. His brother and fiance are early 20's ever since I moved into this house I've tried to be nice to his family, and help here and there because I have my own transportation. Ive had no problems with anyone except up until this point, he also has three other brothers(and they treat me like family) except the brother and his fiance. So here's the rant ever since mid-December I offered rides to him for free up until recently because of the distances(driving there and back is just 30 minutes) but he asks to go other place so that's extra distances, but his fianceee don't get me started she is the most vile woman I have ever seen in my life. Just within the past week she has posted about how her man is stuck at work, and needs a ride. This is how I'm brought into the situation their mom(she tries to help things) so she called us to ask us to get him, so we agree and low and behold once we've got there we came to find he had been picked without even telling us. Just recently after this epidemic we brought my boyfriend brothers clothes to her house along with an early baby shower gift and his brother asks persistently if well say sorry to her about the previous day. We go inside after he like seems to drag on for days asking. So making our way to the door she comes out takes the gift says thank you, goes inside we say sorry but our sorry was directed towards the whole situation not just the ride. And when I tell her over Facebook that her boyfriend asked us to she gets feisty with me and tells me I shouldn't have said anything at all I tried to tell her that we didn't want her upset and she keeps going with this attitude of acting rude to me when I've done nothing but be kind to that wretched troll. Another instance looking back in the past just a couple months ago we brought her fiance to see family over here but shortly after being there she gets mad because I won't bring him when she wants him? Oh, and don't mind my age I know the laws but I suffer from PTSD from being raped as a child so it helps me calm down. My boyfriend and, I smoked pot back earlier in 2016 and remind shes pregnant. They both came to stay the night because it was to loud, and she has morning sickness I bought the stuff it was medical. Yet when we told them no to it they kept asking it made me so mad not only are you pregnant but your rude to me so I have no intention of sharing. So when we finally gave them a bowl(I'm easy going even with people I don't like) then after we have given it to them they tell us they we're about to head down to our room? Ladies this girl is horrendous with her personality, oh and after calling her a rude ass bitch she said she was going to return my present, and called me fake also her sister wants to kick my ass when all I've done is helped. Any advice is appreciated thank you