Is this even fair? wtf...UGH MEN!?

I don't know if it's because I'm a woman, I don't know if it's because of the cultural differences, but someone please answer this one for me. My "fiance" has really been pissing me off. For example, he is mexican, i am american. I have a license, him and his buddies and his mother do NOT. So I had a full time job, ok pay, he asks me to leave my job so I can taxi around his family and friends, with this promise that I can make alot of money and help them out at the same time. At first I was very skeptical, but I said okay due to the fact that I could relax and home and cook and clean more and have more free time. Plus that would mean he would be taking care of everything financially. I finally agreed(because at first I told him no, he begged). The reason why he wanted this was because they're passing this stupid immigration law and he's worried for his friends and family, and the agreement was that they'd be paying me. But as you can imagine, things got tight with the money income change. Ok, I was okay with that, you make sacrifices for the ones you love, got it. BUT THEN his freakin mother hasn't even paid "on her own" till this day! I drive a gas gussling car, I'm not even making a profit here. I drive his mother and her two friends to work every day. About ten miles to get there at FREAKIN 7 am in the damn morning and then I pick them up at 4pm in the afternoon. Thats twenty miles. Then on top of that she asked me to take her son to school and then pick him up in the afternoon too, another 5 miles. Then I have to take my fiance to his friends house everyday at 5am as well so that they can drive to work (he works an hour away). The friend lives about 15 miles away. As you can imagine, making all these trips and BACK every damn day in a car that isn't great with gas isn't good for the gas tank, especially with this ridiculously rising gas prices, and this is on the daily! I supposedly get paid every WEEK! My problem is the mother doesn't pay and everyday I'm stressin out because we don't have gas in the damn car and I can't do wtf I need to do because I'm so busy over extending myself and bending over backwards for these people, WHEN SHE AINT PAYIN. My fiance has to go ask for money, he calls it "borrowing" and im like dude she owes us more than, go ask her for the money that she owes for me taking her to work, and taking her son to school! His response goes a little something like this, "I don't want to ask her for money, besides, that was YOUR GUYS'S deal, not mine, you go ask her for the money." And her refused to do it. I'm so freakin pissed off it's not even funny. Then he gets an attitude like I've done something wrong! well have I?! I've been nothing but nice up until this point but I'm about to snap! This time she asked us to borrow 20$ I only let her because it was my fiance little brother's Bday. I lent her money I really didn't have and she still hasn't paid for her taxi fair or paid for her son's fair or paid me the 20$ back and I'm to to point where I'm not taking anybody any ****** where and going back to WORK!