Hi there, CrazyJim!
Congratulations for seeking treatment and following through! You have a lot to be proud of right there!!
Your peers will just have to get used to the new you. It must seem a little strange for you to see this reaction in them. But, people change all the time and for many reasons. Some simply read something inspirational or a self-help book; some have life-altering events that make them begin to look at their lives differently. At your age, some of your peers undoubtedly are thinking of their future and feeling a little more serious about life than they might have a year ago, for example.
So we all change at different times in our lives. You can share what you are going through with them if you want to, but you owe no one any explanations at all. Or you can simply say "I feel good these days" and leave it at that without further explanation of why you feel better or why you didn't feel well before. They are probably envious of you!
In the end, it is your decision to share or not. (I personally agree with some of your concerns for not sharing.) Your health and mental health concerns are private matters.
Keep up the great work!! Come back and share often with us!