So you'd gptton married less than 7 months before (and a month flies by) and he was already cheating?
Why did he bother getting married?
What does he think marriage is?
What is wrong with his head that he stood up in front of your gathered, joint families, friends, acquaintances etc and made vows to be your exclusive partner, to be each other's life partners. .... And then started a relationship with someone else a few months really later. He clearly takes his vows and commitments very seriously. They clearly mean a lot to him. It's not only the public avowal of exclusivity and commitment, bit of the personal, intimate, emotional commitment he made to you when he married you.
Then there's the fact he also vowed, no doubt, to cherish you, care for you, support you, whatever .... That also clearly means jack shit to him. He's done the opposite, he's betrayed you, cheated on you, and equally bad gas lit you and let you think/made you think you are pathetic and insecure and paranoid.
Integrity - non existent.
This is not marriage material. He really shouldn't have gotten married.
It also sounds like he was going to leave but then lost his "alternative" option.