Sent him a passionate message about how ive loved him for 3 years, how i loved all the time we shared & memories we made. he got upset i said 'loved'

It feels like he's selectively read into word choice in parts of the message and ignored the whole of it. That's the behavior of someone who wants to find a reason to feel hurt or upset.

You aren't in the wrong. I'm not sure what is up with them, but they are acting in a rather toxic manner over it.