one of my closest friends had a sex change,I tell him or her now the same thing.
Just to clarify, people who change their sex aren't "gay" they are transsexual, and it is a medical and psychological term, and considered a neurological birth defect that can only be treated through hormones and a sexual reassignment surgery.
People who are transsexual have either a female brain with a male body, or a male brain with a female body. When they grow up, they become depressed because of this physical and neurological problem, and their brains do not fit the way their bodies developped. By changing, they become happier and themselves.
If a man changes into a woman... and she loves a man, she is straight. Or if a woman changes into a man, and then marries a woman, he is also straight.