Being dumped

My boyfriend of 3 years left me quite suddenly because he 'didn't want to put in so much effort to make me happy' and wanted more time with his friends... I'm dead inside. I have no idea how to deal with this and no one around me understands. I thought I was going to marry him, my whole future was planned around him. I am so empty and heavy inside and I just need someone to tell me I'll be okay. I know everyone goes through heart break but this is my first and it sucks majorly.

Also found out he got with one of my best friends the other weekend and she didn't know that we weren't together anymore. It kills me to think about them together like that, and I've also heard rumors that he was cheating on me. I don't even know how to react a few months ago I was so happy in what I thought was a perfect relationship. I'm so lost, please help 💙