AITA - friend breached boundaries and it took me back to prior incidents

I’m 44M. “Neil” is 45M. We’ve known each other for over 30 years, with some long gaps after fall-outs, but he was always my closest friend and in fact acted as my best man.

We recently reconnected after a couple of years and started discussing a small business project.

Separately, I’d been developing my own idea and sent Neil a draft proposal for feedback. Every page was marked “confidential.”

A few days later he sent me a long critique — except it wasn’t his. Without asking, he’d forwarded it to someone he knew with small-business experience.

Some feedback was useful, but some made sweeping judgments about my temperament, ambition and whether I secretly believed in the idea. It badly knocked my confidence.

I asked why he’d circulated it. He said he was trying to help. I said I’d sent it to him, not for onward distribution. He apologised, but admitted he didn’t agree with all the feedback.

I told him I didn’t think we should pursue the business together.

The problem is that it reopened a lot of history.

About 15 years ago I dated “Sarah,” whom I met through Neil. They were old friends and became increasingly flirtatious while she and I were together. At one party just after we split, I found them alone, drunk. and inappropriately flirtatious. Neil also once told me she was “too good for me.”

I discovered he was messaging her privately. He said he was just supporting a friend. As far as I know nothing physical happened, but I always had suspicions. Months later I found out she blocked him. Why, I do not know.

A few years later, while we were out with mutual friends, Neil verbally eviscerated and humiliated me in front of mutual friends. No real trigger for it, although I had been a bit sullen that night. He never properly apologised. Yet I decided to move on from it after a few weeks. I genuinely wanted the friendship back and had started confiding in him again.

Then, this week, he circulated my proposal, and I thought: why am I surprised?

Obviously forwarding a document isn’t comparable to humiliating someone or crossing boundaries with their girlfriend. But it reopened the whole file.

Maybe I’m unfairly treating old mistakes as evidence of his whole character. The girlfriend issue was 15 years ago, the public humiliation over a decade ago, and this recent incident was thoughtless rather than malicious.

But history matters. If someone has crossed serious boundaries before, perhaps a minor new one inevitably carries more weight.

I keep coming back to this: if I wouldn’t choose this person as a new friend knowing everything I know, why am I choosing him as an old one?

I haven’t ended the friendship. I’ve just stopped making myself vulnerable with him and no longer want to go into business together.

AITA?

TL,DR. Old friend with boundary issues has breached my trust - again.