Get yourself on a plane and get home and away from him.
What he choses to do is his choice be that follow you or kill himself - though I think that is more likely an attempt at manipulation than reality. But if that is what he choses to do - so be it. His choice not yours.
tell your parents, tell his parents. His parents can ‘support him’ which can offset any feelings of responsibility that you have towards him and all his threats of hurting himself.
your parents can hopefully support you.
tell your friends - get support. You’ve done nothing wrong. You do not need to keep his secret - reach out to every avenue that you can.
get yourself to a divorce lawyer asap - get things sorted out.
I would tell her husband - not out of spite - but because he has a right to know - if he is ignorant to all this like you were - you know how he will be feeling. Calmly, gently but factually tell him - he deserves to know so he can make choices.
it is the shock of your life - but you need to protect yourself both mentally and financially.
it is his shame - it is not your shame.
you owe nothing to this man and his bit on the side
you owe everything to yourself to survive this and move forward .
don’t engage with him or her any further - everything through solicitors- you do not need any more of his lies or attempts to win your pity. Emotionally he deserves absolutely nothing from you.
so sorry this has happened to you.
don’t allow him to do anything more - protect yourself both mentally and your oneards life and assets.
cheating scum like him add nothing to your life.
It hurts like crazy now - but you will survive this and are better off without such deception in your life.