Feeling low. Down and losing myself.

2 yrs ago i got to know that my husband has a relationship with my cousin.I caught him red handed , got to see their chats.Though he admittted his mistake and acted to be loyal then onwards he still continued his relation with her.Each time when i question he makes up 100 false stories to coverup.His main justification for this was that i never showed intrest to him.With 2 kids and house hold chores i often get tired and dont always please him when needed.He's a person who gives importance only to sex.now its been more than 4 times im confronting him but always he says sorry and says he won't repeat and keeps cheating me.He is a big time lier and a cheater.He knows well i wont leave him and go because i have no where to go.i cant neither tell my parents anything because mine was alove marriage which took place just because i wanted to.now im getting mentally down and losing myself.