My aunts bf...

Am I being hurtful if I tell my aunt her bf isn’t my sons uncle? She keeps calling him that, but it’s like I’d prefer him not to be called that, neither me nor my hubs like him , and we definitely don’t want him called uncle, since the only significance he has to be is being my aunts bf.. how should I go about saying that to her? I feel like “ don’t call him uncle please bc he’s not” feels rude

UPDATE: so I asked and things exploded. I even admitted to what I said also. Needless to say now I have to have a sit down talk, and part of it is my fault, I admit but I wasn’t wanting it to go as far as it did, so long story short: I asked hey do you mind if we call -bf- by his name instead of uncle his name, as to which she replied back then I’m just -name- not aunt name just -name- I was no your still aunt, id be more comfortable with him being called name instead of -name- i can’t remember what she said after that but I was like what if you break up, to which I also said was not likely might I add, and she was like how long have you and hubs been together I was like 5 years, she says we’ve been together 7, and then started telling me to go fuck myself at that point I followed her out the door bc I was like I’m talking to you and I’m not done which makes her storm back into the house, all the while I’m holding my almost 11mo while being 22 weeks with baby #2, and she’s proceeding to push me with her finger yelling at me, which is upsetting me even more bc I was upset when she said she wasn’t aunt anymore just name. Then my brother comes out and gets in between us and starts pushing her towards the door and trying to figure out what’s going on, and she’s all your saying he isn’t part of the family and I didn’t, then calls my grandparents when I’ve already mentioned I didn’t want him called uncle name in the first place, so I’ll post an update here soon about the end result.