Please help me ive lost hope about my size?

im a very overweight person at 19 stone after having gallstones removed i piled on the weight i become determined to eat sensible now and exercise ive tried to go to the gym that failed after a few weeks as i felt i was being laughed at for being so big with super slims everywhere. now im trying every night walking long distance to build up a sweat and it seems like every car that pes me i fele are laughing at my size ..YEA OK people say lose weight you fat cow but when you try so hard the same people laugh in your face when you do wobble by sometimes i just dont wanna live anymore.what can i do to stop this pain if anyone else has ever felt like this how did you carry on?