Change is scary!
My mother has your same fears.
In her case, she uses her weight as a shield or barrier or excuse or whatever you want to call it.
"I'm fat, therefore I can't/don't want to/won't/no one will expect/ask things of me." "It keeps me safe and insulated from the big bad scary world." Trouble is, it really doesn't.
She's lost considerable amounts of weight several times, but always gains it back with a vengeance.
Beyond that, it's totally wrecked her health. She's now non insulin dependent diabetic, bad knees, bad hips, bad feet, on oxygen at night, bouts of cellulitis, 3 stints in her heart, had to have her gall bladder out, eyes going to heck because of the diabetes, and on and on.
Thing is life will always be life, whether you are fat or thin. Some days will be good and some will be bad.
Being heavy will not save you from life, but thin won't either. Personally, though, I'd rather do it thin/healthy. There are a lot of things I would have never done, or wouldn't be able to do if I were heavy.
Don't give up!