Dear LIB readers: Should I cover my husband's sin?

From a female LIB reader

I have been married for 10+ years and
thought I was happily married till some
weeks ago. From the fourth year into my
marriage my mom advised us to take on 2
female relatives. One was 22 and the other
13 at that time. In 2010, we noticed that the
older of the girls had become so close to
my husband to the point that anyone could
easily conclude they were intimate. She
became rude to me but got closer to my
husband and he never saw anything wrong
with her attitude. He would take her to
school (UNILAG) and pick her up regularly.
He would gladly buy the exact items for her
and myself whenever he traveled. Several
times he gave her large sums without my
consent or knowledge but thankfully it all
came out through her mom. Continue...
He blurted out once that she had STD and I was
quite embarrassed that he would know that about
her if nothing was going on. In the end we
decided she couldn't go on living in my house
and my mom came to take her away her even
though my husband kicked against it furiously.
The younger one stayed on and that is now my
greatest undoing.
She grew up quickly and she is now 20 and in
her second year in University. She recently sent
her Dad (who lives in Lagos) a suicide message
stating that she was going to kill herself if she is
allowed to continue staying with us. Her dad has
now called me to say he followed up with the
suicide message and she confided in him that my
husband disvirgined her at 15 and had continued
to sleep with her till she put up some resistance
late last year. She said he is also with her
roommate and claimed to have seen a message
from the girl to my husband implicating him. She
also said that she had caught my husband and
the older girl that left in 2010 in suspicious
positions before the girl was sent away.
I have confronted him with all these and he is not
giving tangible reasons to disbelieve the girl.
Truth is I know he did these things because of
other things the girl told me that I have since
confirmed one of which is that he brought a stray
girl (18 yrs) into our home under the guise that
she was a distant cousin's daughter. It turned out
he met her randomly and merely chatted her up.
My Pastors have intervened and told me all these
are true but that "he is a man and will never
openly admit it now". They are asking me to let
go for the sake of my children and the marriage. I
am however upset that he will get off this easily
and the innocent girl will not get justice. Should I
cover his sins and appeal to the girl's father who
has indicated that he will do as I advise or
should I insist that he is made to apologize to the
girl? I keep thinking what if she is my own
daughter!! I am at my wits end trying to figure out
if I should act as a wife or a mother! Will a good
wife cover her husband's sins???