Ok, so DP's brother and his wife have recently had their first child. I will say in the first instance that I do not get on with the wife but am civil in family situations. I am engaged to DP and we are marrying soon.
Anyway, when the baby was born I organised a gift and card, we were both very excited to meet the baby, it's the first in either of our families. I signed the card Uncle DP and Auntie me. I know I'm not technically his auntie yet but as we are getting married in two months I didn't think it was worth saying anything different.
Today I received a text from baby's mum asking would I please not refer to myself as auntie because I wasn't even married and they don't want child referring to non-blood relatives as auntie and uncle. I was taken aback and really quite upset, I consider him just as much my nephew as if my sister had a child. I don't differentiate between my own aunties and uncles and love them all equally.
So am I being unreasonable or should I just refer to myself as my name in future cards etc?