Weight loss

I've been trying to loose weight. I am currently 249.8 I was 251.2. I sadly only get support from my boyfriend & his family. My mom and step sister put me down and I feel so bad. I just want to loose weight to prove them wrong. I just wish I actually knew how to do it, than just exercising. All I've been eating is salads. But I'm doing it and I'm gonna work hard!!