Need advice for my current situation - possible love triangle?

Looks like you have gotten yourself in a sticky situation. You should leave the decision up to Tyler. Tell him to do what feels right to him. They will eventually break up if there relationship keeps going downhill. You just have to have the patience to wait for him. If you cannot wait for him then that means you don't like him enough and it wouldn't be worth it to break up a friendship over. Once they break up for a while and they have both recovered would be your time to move in and continue with a future relationship. Hope i helped. Good luck.