It sounds very much as though you're suffering that phenomenon: careless family members.
I suggest two strategies. You can either use them in concert, or pick the best one for you.
1: Respond to snide comments with equally snide comments. If someone who should love you for who you are says "That top makes you look fat," try "Those trousers make you look ugly." If they say "You've still not lost any weight," try "And you've still not grown any manners". It might descend into a slanging match, but they'll soon learn that you won't tolerate the constant put-downs.
2: Communicate. Sit whoever it is in your family down (I'm guessing mother, right?) and explain calmly and clearly that while they may believe they are encouraging your weight-loss, all they are doing is making you feel bad and you want to give up. Tell them that if they really want to help you out, you have a list of ways in which they can do so (I don't know if you live with the offending family member(s) or not, but it might include not keeping fatty / sugary foods in the house, not insulting your weight, etc).
Also, are the people who are putting you down overweight themselves? Often the family member is actually feeling just as bad as you are about their own weight, and are transferring their self-loathing on to you instead. Or if it's a parent they may see your weight as an everpresent visual reminder of how they personally have "failed" you by letting you get overweight in the first place.
Then there's just the fact that some people really don't understand how fat people could possibly have got so large in the first place, and they figure that there must be something "wrong" with you. Which is always charming when it's your own family doing it. Are the rest of your family naturally fit, healthy, and healthily-sized?
Realistically it is YOUR body. Nobody else's. It doesn't matter what anyone's opinion of your body is, because they don't have to live in it. YOU do. It is your responsibility to ensure you live as happy a life as you can, and if you want to lose weight, you go do it! Don't listen to your family's put-downs, don't listen to anything which doesn't help you lose weight.
If something exists in your life which has no value to you, remove it from your life. Your family's comments on your weight? No value to you. Discard them. Don't hold on to them, because they are NOT precious pearls of wisdom to be treasured. So what? You're overweight! Do they think you haven't noticed?
Seriously, you can do this. Of course you can. And no amount of anyone suggesting or saying that you can't is true, because they can't force you to eat. Only you can choose what eat, only you can decide when to exercise, and only you live in your body and have the right to choose what you'll do with it.
Sometimes you just gotta tell them to shut it
