How do I file for divorce if I do not have money for large attorney fees and we have a son together that I don't want him to see?

Unfortunately, due to the issues surrounding your case (having children, one of whom has been abused by your ex husband), it will be very difficult for you to pursue this case on your own. You want to ensure that you receive as many protections as you can for your children as well as whatever you are entitled to financially (child support, your share of community property, etc.). As such, I recommend contacting several local attorneys and asking them if they offer payment plans or alternative billing arrangements to handle cases like yours. If you don't find any attorneys willing to take your case at a reduced fee or willing to make payment arrangements, my next suggestion is to ask for help from close family and friends. You need a qualified attorney's representation for the best possible outcome. Good luck.