Hmm, well, I was the guy in this situation with my ex who actually did shitty things and was dishonest in a way it sounds like you never were.

My ex said she and I were going to get married last Sunday and then ignored all of my calls and texts all week and when I went over to her house to see what was up, she said there was a mysterious friend over. But she locked the door and wouldn't open it after I had politely knocked and just asked to talk. Instead of talking to me, she threatened to call the police on me, so that shit escalated really quickly and I started crying on her doormat a lot.

I regretfully spouted in a fury of sadness and anger that she was an alcoholic and drug addict outside her door in her complex with families around and called her father to say the same thing. Which, she herself, admitted to the former that same Sunday having spent two days straight doing nothing but drinking and not eating any food at all - again, by her own admission. I was crying and I told her dad that she needed to get help and that she had broken my heart. All weak moments for me which I regret because I shit all over her (but, I mean, she fucked me over for years with this shit) and it made me look like I was trying to get all buddy-buddy with her dad. which maybe, subconsciously I was trying to do to somehow how some last effect on her life and his by extension.

What I'm trying to say with all of this rambling text is that it's really fucking hard to know what a lost, really intense feeling of love can do to people. Or what pride can make a man (or woman) do in spite and anger and hurt.

For my case, which is totally different than yours it sounds like (your ex is really overreacting with all of this shit and needs to calm down on his own), I had constructed an idea of a relationship that clearly was not in existence with my ex.

James clearly created an idea of his time with you that you did not share with him. He clearly had some deep-seated suspicions about you and someone else (sam) before you guys broke up and he clearly did feel betrayed. I'm not saying rightly or wrongly, but he did feel betrayed regardless. He's taking it to a now crazy degree though and he's clearly upset your parents so much so that he has made a big reach into your life.

But here's the part I want you to think about: You emotionally cheated on James, you even admit to making "poor decisions" about it. Emotional cheating is the exact same thing as physical cheating. When you started developing feelings for Sam, it makes sense not to tell someone else you've established comfortable boundaries with and you want to see if this other thing is going anywhere first.

Which is cheating. Emotionally at least.

It doesn't make you a shitty person, it doesn't make you anything less than human, but it's clear it gutted James, badly.

He had no right to get into your email, however, and I would change ALL of my passwords on everything, immediately.

Regardless of the past, James is walking a tightrope now and is trying to hurt you and affect you. The fact that your parents sided with him though would make outsiders probably pause because whatever he said must have been serious enough to convince your parents (the people who are supposed to support you no matter what - at least theoretically) that you needed help. If he really did lie horribly about things, then fuck him, he's an asshole. But, do you actually drink a lot though? Most people who happen to drink a lot also happen to not admit to how much they drink and how frequently they drink and how they might change when they're drinking - just a thought.

Anyways, I hope things work out for you and I hope things work out for James too. People who once cared about each other don't need to bring out the knives over this stuff but it happens all too often.