I cant tell if they are using triangulation or if i am?

I was casually seeing someone whom i believe to have a lot of narcissistic tendencies. Things didnt work out and it only lasted a few months.

I reached out to 1 mutual friend for more detailed advice and to check if i was going insane. I felt absolutely insane most of the time. I also vaguely reached out to another mutual friend but i didnt really go into detail for fear of it looking like i was talking shit on them.

I had 2 decade long friendships (not the same 2 people i had spokem to about the situations we had) and i has briefly introduced my now ex and them together. After we broke up and it was super messy i was trying to move on and heal. I had asked my friends to please not talk with her because it was very toxic at the end. They had no issue with that but still kept in contact.

Now my ex has told my friends disgusting lies about me and they never really defended me just let my ex say anything she wanted.

Now they told me to get lost saying the things my ex has been saying about me paints me manipulative and accuses me of much but im really stuck on the triangulation part. I never thought i did that. I didnt even know of the word before all of this. Im not sure if seeking advice on how to handle our fights with 2 friends is triangulation. I always made sure to tell my friends before, during and after advice that i didn't want this to paint my ex in a bad light i just needed reassurance and advice.

Did i lose my long time friends because i triangulated or because my ex did? Or am i insane right now?

Im sorry for such a long winded post im just confused and upset by my life falling apart over my ex.