OK, imagine the damage this will do to your self esteem over time? Not massive to your face attacks, or though I wouldn't be surprised if it did happen. sadly.
So you are with someone who you like, who belongs to a family that on some level(s) doesn't think you are good enough for their boy.
Not the right religion - so bless you, you end up converting, but then there is the other issue... your colour. Then the DS from another relationship.
Honey, we all know there is nothing at all the matter with any aspect of YOU as a person, whatever religion you are, whatever colour you are or whatever your family history. it's YOUR business. Trouble is, they are showing signs of disapproval, and it'll get worse.
My concern is that even if it's very subtle, the slight knowledge that they are looking down on you out of religious or racial bigotry, will harm your self esteem long term, and you yourself won't have the power to stand up for yourself against his family. He already isn't standing up for you, he is only putting his toe in the water. After his sister said "Well, as long as they're muslim its ok" WHERE was his "..and if they're not???? WHAT???" Challenge
Quite simply YOU are better than this relationship! YOU don't need to settle for this, you need to be with a man who whole heartedly loves you and respects you, and is willing to stand on the top of a mountain and shout it for all the world to hear, not cower behind the sofa if his Dad rings.