The best thing to do is take each day at a time, don't think about yesterday, or tomorrow, just focus on today. And what I find helpful is not to think of it as a diet, just think that this is how everyone healthy eats, and your just taking some time to adjust to it, but eventually you won't struggle with it, its just about breaking habbits!
It's also good to have a support system who are really strict and nice, family and friends need to help with this too, and good to talk to! And keep looking on here at people who are doing really well and think that you will be one of these.
To make things easier it might be a good idea to make lots of smaller goals, you could make your goal half a stone, then when you reach that you will feel like you accomplished something, and so on.
Good luck, nothing that was ever worth having was easy to achieve x