I need help with my Mom.

Hello everyone, Sorry in advance for the long post. TLDR version at bottom.

I've been lurking around this community for a while. I'm not overweight myself but have been close and recently lost around 15lbs to get down to a mid-range normal BMI. The last 15 or so is the hardest to lose and I've enjoyed the tips and tricks found in this community. I've discovered a new passion for running and fitness and feel better than I've ever felt.

But this post isn't about me, it's about my Mom. My Mom has Hashimoto's. In short, she has hypothyroidism caused by her immune system attacking her thyroid. She takes medication to boost her metabolism back to normal but has struggled with her weight her entire life. It got much worse after she had me (her only child) and I'm convinced that her weight and general lack of enthusiasm for life destroyed her relationship with my father, a tall and skinny life-getting kind of guy.

I essentially grew up on a diet. I didn't have real bacon (just turkey) until my early teens, I didn't have sugary soda until then either. We grew up on margarine and weight watchers plans because my mom had instilled this fear in me that I might one day be like her. I always figured that my mom had it pretty much together until I recently moved back in with her. Her lifestyle is far worse than I ever imagined and to see her like she is breaks my heart. Not only this, but it annoys me for some reason. I feel terrible for it, but I can hardly stand to be in the same room with her sprawled out on the couch and huffing and puffing like she's about to pass out.

I would say she is about 400 lbs or more. It's not exactly Grapes of Wrath in here, but it's well on the way. She comes home from work and immediately plops down on the couch and turns the TV on. She breathes heavily as she sits there. Midway into the night she'll say her hips hurt from sitting and she'll lay down on the couch and dose off, breathing heavily and snoring. We don't do anything together after work because she's always too tired. We don't do anything on the weekends because she's always too tired. We don't do anything that involves any kind of walking because she can't handle it. So despite the fact that she's only 50 years old, she cannot even walk around a mall or public area. She wakes up every hour of the night, which I attribute to sleep apnea. She has to "two-step" the simplest of stairs and she will circle a parking lot 5,6,7 times to get the closest spot possible.

Because of a messy divorce she has no self-esteem. Every time I try and suggest something, like doing a water aerobics class (she always complains about her knees) or even doing exercise on a bicycle (the one with her feet out in front of her) she takes it as me insulting her and hurting her feelings.The more you "push" her the harder she digs her heels in. She buys fattening foods and is oblivious to labels. She's one of those people who simply reads whole grains on a box and assumes it's a healthy snack. Everything she buys is full of sugar. When I press for her to get fat free salad dressings, skim milk, cut back on cheese and whatever else she quips that all of that is "disgusting" and basically gets in this "I'll do/eat what I want" kind of mode.

After "losing" my Dad, she settled into this bitter lifestyle. She has no idea who she is. She's an extremely private person so talking to a therapist is out of the question. I feel like she's waiting around for something to push her into inspiration like we all owe her a sympathy vote because of the divorce she went through but at this point, 6 years later, she no longer has a sympathy vote and is pretty much just pathetic.

I'm writing all of this because I fear for her life. Growing up, despite her weight, she claimed she was "healthy" with good blood pressure and cholesterol. Now I'm convinced she may just die in her sleep because she'll stop breathing. I'm also convinced she likely has diabetes or is pre-diabetic due to her complete lethargy.

How do I help her? Has anyone here been in her position and found a way to the light? Is there some magical combination of things I can tell her to get her to see that this is all about her and no one else? At this point she will die a bitter and miserable person and I will feel somehow responsible for not pushing her hard enough or telling her the right things to boost her confidence. It's gotten to the point where she annoys me, her lifestyle annoys me and her lack of interest in anything involving physical effort annoys me, so I'm distancing myself only to feel guilty.

Is there some kind of intervention I can stage for this? A magical book? Or is she pretty much helpless until she helps herself?

TLDR: My mom is obese and lethargic and cannot seem to help herself. Her lifestyle annoys me while I simultaneously fear for her health and life. I'm wondering if anyone has any advice on how to deal with her.

Edit: I invite anyone downvoting this post to explain why. Please. If I'm doing something wrong here, I need to know. I need an outside perspective on this.