I keep hearing nightmares about whrt got small cell lung cancer that can go to the brain mine already is in my brain I hav 10 tumors is whrt bad?

Serious, treatable. Someone with this problem ( small cell cancer that has spread to the brain) is facing a very very difficult and serious health issue. It really needs to be discussed with ones doctor. This can be treated, but the details of the expected outcomes and things like that really need to be talked over with one's personal doctor. Every situation is a little different.
WBRT not bad! Whole brain radiation is the standard treatment for small cell lung cancer that has spread to the brain. Although there are risks to wbrt, the evidence is very clear that the bad consequences from untreated metastases are generally much much worse than effects from wbrt. In some cancer this is controversial, but not in small cell!
It is serious. Small cell lung cancer very commonly spreads to the brain. With ten lesions you definitiely need whole brain radiation. Sorry for the bad news.