Unsure about the title but you are under no obligation to give it. Perhaps say you will inform the other friend that the other is trying to get in touch and leave it to them.
I know I said person but she is a friend too - who hasn't seen this other friend in about 40 years - but recently seen her at a funeral and couldn't get over how bubbly and happy this other friend is - other friend was acting out of character.
This other friend is no way happy or bubbly but is suffering from a deep depression and sadness and I don't want the first friend to know this. Sorry for confusion.
Really? It's not like a phone number. You can ignore emails. Look how many people and firms have our email address. If you do anything online you give your email address. What harm can be done?