I'm so sorry, Christable! It's so awful when parents play favorites! And so often, unfortunately, the pattern seems to extend to the GC. Fortunately, I haven't suffered such "years of hurt." But I totally feel for you. Hugs!
I know you didn't ask for advice, but I agree w/ Septima that it would be better for you to avoid events where both your parents and brother will be present. However, I know there may be occasions where you can't. At those times, IMO, you and DH (dear husband) should try to ignore your parents behavior or make a private joke out of it, maybe guess how many times they will "slip" and speak to someone else or how far they'll go to please your brother and his GF (girlfriend).
"They have no time for me, or my husband or their grandsons. I find it very hurtful. "
I'm sorry you find it so hurtful, but, IMO, you are probably better off not being around your parents too much, sad to say. Especially given their racism. IDK if DIL(daughter-in-law) is a different race than your family or if your DH is or what. But I wouldn't want racist relatives around a mixed-race child. If nothing else, I believe DS (dear son) and DIL should keep their baby away from your parents as much as possible. It's wonderful to have GGPs (great-grandparents) but not if they are prejudiced against you (general GGC). But that's up to DS and DIL, of course.