My blood type is Rh negative what blood type can my husband be so that we can have a healthy baby?

Depends. If you had weird medical care in the past that included a transfusion of Rh positive blood, or a similar medical event that triggered anti- Rh antibodies, you would have problems with any Rh + hubby. If not, any type with positive or negative would be okay. Modern obstetrical care has made the once important issue of blood types more a nuscience than a threat.
Any type. Assuming that you have not been exposed to another blood type (transfusion or previous child) the husband can have any blood type for you to have a healthy child.
Any blood type. The scenario you are referring to is the concern that a rh(-) women has a child with a rh(+) man. A women could develop antibodies to rh (happens in 1st pregnancy - causes no problem) and this could cause issues with her 2nd pregnancy. These problems can be dealt with without difficulty. You just need good prenatal care. The most important factor for a healthy baby is to find a loving husband.