Hi empath -- I don't usually visit F&F, but your thread title brought me in. Just to say, I very strongly believe that human beings can be hurt, but never broken. Treat yourself gently, and you *will* recover.
Welcome to the forums, Imisshim01. About your "why" did he do it? Did he want to upset you and cause a breakup?
Addicts always either move into turmoil, or create it. Their addictions feed on pain. There's really not much point trying to understand an addict. Hey, I'm an alcoholic, and I've given up trying to understand my addiction
All you need to know is that you cannot and must not trust him, not even for an inch.