If the D.A. knows the victim in my case, is this conflict of interest?

Not necessarily. Legally and ethically, a conflict of interest exists when the legal representation of one client will adversely affect the legal interests of another client. Because  the D.A. are supposed to represent the interests of the public at large, a D.A.'s relationship with a victim is generally not grounds for a conflict of interest. However, if you or your attorney believes that this personal realtionship will in some way be prejudicial to your right to have a fair trial, then this issue needs to raised to the judge for the judge to decide if a new D.A. needs to take on the case.