I Caught My Husband Sniffing My Niece's Pants

I caught my husband of five years sniffing the panties of
my 15 years niece. I don't know if I should confront him or
let the issue lie.
I also think he bought my niece a new blackberry phone
because the day I insisted on making my niece tell me
where she got the phone, he became too overprotective of
her and we almost fought over the issue.
My niece recently lost her father, making my sister a
widow who let go of her children to stay with her relatives,
that is how my niece came to stay with me,
On the 26th of November 2015, I saw him at the backyard
next to the heap of clothes my niece brought out to wash,
he picked up a pant, my niece's pant and sniffed it, I almost
screamed where I was.
Also I keep noticing the look they exchange, very
flirtatious.
Lastly my niece is acting like she is his wife, she dishes
his food even before the children's food, doesn't knock
before opening the door of our bedroom, and the most
disturbing is, she asks my husband where he is going
when he wants to go out as if she is his wife, my husband
is 37 and this girl is 15, I suggested to my husband that
we send her off to a boarding school, he rejected the idea
and even got angry with me saying it will affect the girl
psychologically, as if I want to dump her in a boarding
house and run away. I want to confront my husband but I
have no evidence, and for my niece I respect my eldest
sister so much that I don't know what to do, I feel like an
outsider in my own home.
P.S. My husband is a banker and also a pastor at our
church.
I sincerely need your advice.
Thank you.
Sad depressed housewife in Ikeja