Taking back my life

Hi my name is Courtney and I am 39yo. I have spent the last 15 years battling with my weight, I've tried countless fad/yo-yo diets only to lose a little and gain back twice as much as I lost. My current weight is the highest it's ever been and after some recent health issues I have decided that it's time I take back control of my life and my health. I have high blood pressure and PCOS as well as osteoarthritis and psoriatic arthritis and I was also diagnosed pre-diabetic a little over a year ago. I was diagnosed with cervical cancer almost 2 years ago and underwent a complete hysterectomy with bilateral salpingectomy-my ovaries were left alone due to my age and thinking it would delay the onset of menopause for at least a few more years however 2 months post op we learned that didn't work out as planned. I'm cancer free now though so there's that. I have around 125-150lbs I'd like to lose, however my main goal is getting my health issues under control, reducing my blood pressure and a1c and improving my mobility and overall quality of life. I lost my dad at the age of 42 and the thought of dying so young and leaving my 2 children without a mother scares the living hell out of me. I need to do something different because doing what I have been hasn't proven to be successful.