It almost sounds like your mom is more concerned with herself than your health... Who would she have to nag if you were to die suddenly because you went her way of not doing this... You're doing the right thing for you...
I'm there with you... I'm 39, 5'11" and weigh 324... I have a great confidence about myself but I want to be healthy for myself, my kids & my hubby... My mom died back in 2001 at 58 yrs old weighing over 400 lbs and had all the complications that come with being that heavy... If she were here she would totally support what I'm doing...
Once you get to the size we are "normal" ways of losing weight don't work as well because of our limitations with the weight... Once the banding is done and you start dropping weight, you still have to workout to get your muscles toned and skin back where it belongs... Banding is not the "easy" way out because of all the tests and prep we have to do to even get scheduled for surgery and what we have to do after to keep the weight off...
Your mom needs to back off or you need to just ignore her comments... What your mother doesn't give you in support you need to get from yourself and the positive people around you... Good Luck