I'm sorry to hear that you've had to deal with a drug addiction.
About losing weight. I'm not sure if you're aware, but you're right in the middle of a healthy weight for your height. (143 lbs)
In fact 45kg (about 99lbs) would make you
severely underweight. The only people I see trying to lose to that amount are almost an entire foot shorter than you.
We'd all love to help you eat healthier and to keep you exercising. But I gently suggest you rethink your goal weight. For your own health.
All the best to you.