There's no need for us to tell you how it is. You know you're overweight.
Losing weight is 80% diet and 20% exercise so for now, if you're finding exercise painful, don't stress about it too much. Focus on your food.
You also sound like perhaps getting back to your 9st body is your ultimate goal. I would say drop that goal - for now. If you give yourself a mountain to climb right off the bat you'll never get there. It's too difficult, psychologically.
So start small. Very small. Give yourself a target of losing 2lb this week. Then the next week. Then start to think of more long term goals. E.g I want to lose 15lb by 1 July.
If you can lose 2lb in one week, then you can lose it the week after, and the week after that and after that and so on, and eventually you will get there.
By focussing on one week at a time, it also eases you into your new diet. It means you only have to think about dieting for one week at a time, rather than for the rest of your life - again, breaking down those psychological banners.
Do not start looking towards being 9 or 10st in the early stages. Whilst it can be an ultimate goal, if that's all you're thinking of you will become disheartened very quickly. Losing weight is a marathon, not a sprint.