confidant

uskottu a person in whom one can confide or share one's secrets: a friend
1675, w:John Dryden|John Dryden, Aureng-zebe, William Miller (1808), page https://books.google.com/books?id=KPoOAAAAYAAJ&pg=PA223&lpg=PA223&dq=you+love+me+for+no+other+end+than+to+become+my+confidant+and+friend+dryden&source=bl&ots=9C7--Vk9MH&sig=ijsttJA3UdsCaoh1PnEo3Q2I1H0&hl=en&sa=X&ved=0ahUKEwj04KfA99DJAhUE2GMKHZrHBEwQ6AEIMDAGv=onepage&q&f=false 223:

Heaven made you love me for no other end, / But to become my confidant and friend: / As such, I keep no secret from your sight, …