No. 1 is the wife.
No. 2 is the mistress, which I am.
No. 3 is the woman who now makes him happy as I, like No. 1, does not interest him anymore. This girl is now the woman you once were. Vibrant, exciting, no-emotional baggage, non-demanding etc. This is now the woman he lies for with you. This is the woman you want to be again but its too late as you’ve now became No. 1 in essence without knowing it.
You are now the woman who chose to be content with the very little time he wants to spend with you as he has just added one agenda on his list of family, work, friends, interest, No. 3 and No. 2. (in order).
I guess the question is “How can you be No. 3 while being No. 2?”