I feel competitiveness with her, thinking she's prettier, better lover, more adventurous than me, smarter than me ... blah blah blah. It gets really exhausting actually!
How about giving yourself permission to be yourself, and not her? This is anxiety chatterbox from the sound of it. What are you anxious about? What do you fear?
I also have thoughts that she likes him better than me, but I'm trying to put them to rest as well. Her and I try to have some sort of intimacy/sexual date night/alone time at least once a week.
Do you need to hear that she likes you? Could ask her. "I need to hear that you like and love me. I'm struggling with jealousy head noise right now and hearing your actual voice would help turn those down."
Are you getting enough time with her? Are you competing with HIM for her attention? But not realizing it?
I struggle with compersion - a term I just learned tonight. On a rational level, I'm super happy for them and their relationship. On a irrational (more selfish level), I feel jealous, anger, etc.
Were you expecting "compersion" to come instantly?
You have just changed from a 2 people thing to a 3 people thing and that ups the polymath
significantly. Restabalizing all those "mini relationships" inside the new larger polyship takes time.
Most of that is happening in your "thinks" -- it's ok to answer BACK to thoughts. You are not your thoughts. You are the person doing
the thinking. If I wake up in the night and think I see a burglar and it turns out to be the tree outside shadow? I can update my first thought. I'm allowed.
Could ask for reassurance from your people, and if you find yourself thinking weird stuff, investigate to see what is perceived reality (that might be faulty) and what is actuality.
Don't know if these could help you articulate what your jealousy (or envy) is about
Hang in there!