Leave him alone and distance yourself from him. If he's loving on your friend and looking at you, he already knows that you like him. Best thing for you to do is to save your friendship and not be the third wheel.

I wouldn't trust him if he's flirting with you while he says he loves her.

It must be hard though sending you hugs sister x 😘 🤗

The moment he leaves for you
You have opened up a can of worms
A) If he can do that to her he can do that to you.
B) you will have lost your mate
C) you may end up not liking each other based on the above.