Welcome to the forum
I'm only just into my weight loss journey but if I could offer any advice it would be, just do it, don't put it off start getting rid of that weight today, don't make excuses, if you stumble along the way get back up and keep going don't give up, it will get you no where. Also find something that works for you, I started off using the calorieking website to track my daily calories, I found it great to keep you accountable for what you put in your mouth in the first few weeks, lots of members here use the site too. Don't look at the large number of kgs you have to lose, take it one day at a time, it can be too daunting looking at the big numbers take it 5-10kg at a time, 5kgs might not seem like much to lose when you have much more to lose but honestly even after 5kg loss you will feel better then all those little losses add up and you feel even better as you go along .
I know a lot of people here can sympathise with the struggles you face with yourself and your self image, you are definately not alone. I have very low self confidence and I too hate socialising, buying clothes etc. I am starting to get a bit better so I really do think when you start looking after yourself and can see the improvements in your image you start to get in a better headspace. Well thats the case with me anyway.
Well good luck with your journey, hope it goes well
Remember you can always jump online and post on here, most the time you get great helpful support and if nothing else it sometimes helps to get you feelinsg out and vent your frustrations