Cheated by husband, depression. Resign.

Husband involved in female friend since 2006, caught red handed twice, no proper explanation, bad behaviour with daughters, am working outstation, too much depressed since 4 months.. Though he do household work in my absence, cooperates well in daily chaos, not having conversations with daughters. Ours is nuclear family without any support from relatives since childhood my daughters are struggling but no love and​ affection from father. I am staying alone in the town for working, with family on weekends, trying to please everyone in my presence, but husband not involved and interested in three of us. Caught his messages on WhatsApp with her, gave him option, me or her, he chose me, improvement in behaviour but not ready to tell full story said he will tell, but just admitted for his involvement. Always hide mobile, not ready to share his password, since I am not with him all the time, am not sure if he's not in touch with her. I am confused, loss of sleep, depression, wish to resign.