That's not at all fat. That's a healthy weight for 5ft7. I am 5ft4 and I am about 140 kilos. I wouldn't consider myself fat, although bigger than others. 10.3 stone is a really good weight for your height. I think your issue is that you've put on a bit of weight quite drastically and so it hits you hard. I went through a rough patch for the past 18 months and I put on 4 stone- I went from 8.5 to 12.5stone and I was really depressed because it seemed really quick. In October I decided enough was enough and have dropped back to 10 stone, still wanting to lose more weight and get back down to 9/9.5 stone.
Have you eaten more recently? My issue is that I comfort eat- when I'm mad/stressed/upset I eat food even when I'm full up, I've trained myself now to not do it- although I've gone through various bad habits, turning to smoking and caffeine (I've weaned off the cigarettes and just on the caffeine now), but just train your stomach. The first couple of months are really tough mentally but if you're that unhappy you will do it regardless until it becomes quite easy from thereon!
I hope you get the results you want. If your eating habits haven't changed, may be worth seeing your GP about a hormone imbalance- things like contraceptive pills, anti-depressants can cause weight gain quite quickly, so worth checking it out.
Get out exercising- it's good for the mind too. I ride my horse everyday and walk about 5 miles a day which helps me feel good inside and less stressed- now is the best time of year to get into the swing of things too.
Good luck x