My MIL calls my son a slur and says it’s not

Okay so I won’t make it long or atleast I’ll try not to but I’m furious this really irritates me to the point my blood boils. I’ve been polite too long and now I’m about to get really mean about it. So racially my MIL is Puerto Rican not mixed her husband is black so my fiancé is mixed m. I myself am black not mixed. So when she watches my son or greets him she calls him a “negrito” ...... which is very racist to me and even her son my fiancé has told her that’s not okay and she just brushed it off and continues Also my fiancé has a child from a previous relationship she came out much darker than my son and has course hair whereas my son has fine hair and the nickname she has for her is “monkey” ..... yeah let that sit in. Sooo unless you’ve been living under a rock your whole life everyone knows that calling a blank woman “monkey” is a racial slur the same as the n word and again her son told her about this and she again brushed it off. I get that it’s his mom buuuut this is my child and I’m not about to let her talk like that and say “she has a strong personality as she loves to say” that has nothing to do with anything. She says their terms of endearment. Sooooo do you find it racist?