weight 240 need help with motivation to do it the right way

I'm 5'5" and weight 240 lbs when holding all my water and food waste in. I'm about 235-7 after I drink a ton of water and take a laxative. now unfortunately I have to take laxatives to poop I've tried to natural ones and they work for some time but then stop so my routine is like this. I basically have a bm once a week twice if I continue to drink lots of water and watch my eating habits. I've always had trouble having a bm but since I had my son 5 months ago it's gotten worse. my lowest weight was 160 when I was 18 I did that by walking everywhere literally everywhere ate maybe once a day if I was lucky and I wasn't in a good place emotionally or mentally. now I'm 22 years old going on 23 I'm the happiest I've ever been but I hate myself and I hate my weight. i have what my psych doctor says as borderline personality and eating disorder. I have made myself throw up, and starved myself on multiple occasions and have lost weight and kept it off. now being a mother and having a loving husband who knows my past issues I don't want to hurt my family. and my husband watches me like a hawk. even when I was still at home I did dance classes and sports pretty much 5 days a week but still gained weight. I know diet is a big part of weight loss and I am willing to change my ways but motivation is hard for me. I hear a voice saying starve yourself throw up don't eat that. look at your fat just sitting there. and I freak out. I need help