Baby mama drama (vent)

My fiancé and I have been together about 3.5 years now. He has a 6 yo son with the worst type of woman. Drug addict, constantly getting arrested, crazy ass woman! I have had an on/off relationship with her. Mostly just keep to myself and let her do her own crazy thing, I don't need her drama. Throughout our relationship she has pulled a few stunts and a few times she will get his son involved. This most recent one has me FUMING! We are expecting our first child together this October and we plan to name her Vanessa. Apparently she decided to tell their son that it's a strippers name.. So that's what I got to hear last night when I saw him. "My mom doesn't like Vanessa cause it sounds like a 'sugar'." Obviously he doesn't know what all this means but I'm just livid! Mind you she has two more kids of her own a girl named Serenetey and a boy named Triton... (This is how she spelled them, no typo here!) This may be pregnancy hormones but I'm just so sick of hearing her BS! But I avoid confrontation so I won't say anything to her ugh I'm just so annoyed.