What I find to be the most disturbing is the fact that he seem
to peep at you or leer at you when you are at the kitchen.
That means that there is a chance that he might have some sexual
thoughts or sexual fantasy about you.
This means it is rather unsafe for you to stay together with
him.
Regarding masturbating.......I have no comment because in a way
it is one's own personal habit and one's own individual
business.
But leering at you, is, something that is affecting you and is
no longer a personal issue.
To me I think it is unacceptable if he has done that, because he
has failed to control himself and respect you as a new family
member, and it is taboo and forbidden to do that because it can be
considered as incest, it is something that is crossing the line. If
he takes you as daugther-in-law, he should have 0 sexual thoughts
whatsoever.
So for your case I would be more concerned about your safety and
security.
I think you must find a way to live on your own.
You can think about this and find a strategy to talk to your
husband. I am not sure whether you should be open with him and tell
him 100% or whether you should find some other excuse. The choice
is yours. But if I am you I would definitely start thinking and
pushing in that direction.