For me, I always expect betrayals, but I am most upset when I see them occur at (what appears to me to be) the expense of the betrayer. For instance, our UTTER HELL game could have easily ended a 3 way draw, and a solo was fairly unlikely, but instead ended a 4 way draw due to the betrayal.
I have another example, this game:
https://vdiplomacy.com/board.php?
gameID=39583#gamePanel
Where the Nords betrayed me because I was going for solo, but it was PPSC, so they got less points forcing me into a four way draw rather than finishing in what could have been essentially guaranteed second place.
That being said, we all make our own risk/reward analysis, and just because I think your decision was riskier than it was worth, doesn't mean you're in the wrong.