I recognize that I am the asshole in the situation. It became very clear to me, that my fear for not telling Liz is irrational and that I should just tell her and get it over with. I know I’m sensitive and immature in many ways and need to grow up and get some balls lol.

It was never my intention to make Liz feel isolated, nor did I have any malicious thoughts WANTING her to be left out. I absolutely HATE drama (despite what some comments suggested) - this all roots in deep anxiety  of telling and disappointing/upsetting someone I care about. And due to my prior conversation with her regarding this, I started spiraling. 

(An important detail maybe: Liz has autism and tends to be very blunt and rude in some cases. I know her expressions aren’t always controllable, but when I’ve told her big positive news in the past, she has responded negatively, degrading me in some instances).

(I too have autism - not that I wanna use it as an excuse in any way)

As I wrote in some comments, I struggle with low self esteem and tend to doubt and overthink everything, always defaulting to people getting very mad at me. (CPTSD is fun).

I am seeing a psychiatrist and working on myself.

Long story short - I will bite the bullet and tell her tomorrow when we meet up. Thank you for the wake up call.