Is this regular in your relationship?
If not, I think you need to separate this from your experiences of past racism. You may not currently be able to, as you find those, understandably to painful.
However, if this is not usual between you too, I think you’re overreacting. I say this as someone who is married to someone of a different race, Nd neither of us are white British people, both of us have frequent experiences of some really nasty racism. I’ve had death threats, it’s not something I take lightly.
However, In our relationship we make jokes that reference stereotypes of the other’s race. Neither of us find this offensive or upsetting. I don’t feel my husband defines me by my race, does yours?
If he is actually racist, why did you marry and have children with him? Or is he insensitive to you and made one bad joke? Speak to him, write to him, when your calmer and able to explain your feelings. Maybe your incompatible but if that’s due to his racism, surely it would have come to light earlier.