Your friend is wrong. There is no such thing as past lives; there is one life after which we pass on to eternal life.
They are correct, Jesus did meet many people with various ailments. That said, don't be depressed. God/Jesus loves you more than you can imagine. Even when we struggle with sin, He still loves us, so do the best you can.
I have no idea where you are spiritually, but I would recommend you make an appointment with a Catholic priest to get some advice. Even if you are not Catholic, I'm sure he may be able to provide some time and, if not, refer you to a counselor who can address the issues you have.
For short: Keep your head up high and know Jesus loves you immensely and when you suffer: joining your sufferings to His, can bring in big blessings for you.