What's your relationship with your parents like? Is it the kind where you can ask them to sit down and talk with you about this and be very honest with them, both about your actions, but also about your feelings? I think it sounds like you also need to try setting some boundaries with them, like making clear that who they find attractive isn't about YOUR dating life (it's about theirs), and you want them to stop putting that on you, and also asking them to please respect this is the relationship you have and to stop trying to set you up with other people. I would ask them to be supportive.
All of this of course may be difficult if -- and I agree with Mo here that it likely is -- racism is part of this picture. Just because they're Mexican -- and he's half Mexican himself doesn't mean they can't be racist. There's actually a lot of racism against Black people in a lot of Mexican families and communities, unfortunately. But you're probably going to have better success talking about the things I mentioned above, or at least starting with those, then coming at them head-on to talk to them about racism being a likely part of this.