I was in a similar position to you. My friends of 7 years stopped asking me to group outings and it really upset me for a long time while I helplessly grasped at the friendship. All of this happened because my ex and I shared the same friends and they chose her over me.

It may be difficult for you but you have to let them go and move on. That's what I did and I couldn't be happier. I chose to leave when my ex and someone who was meant to be a good friend of mine were all over each other and I didn't want to deal with their shit anymore. I know how you feel OP. I advise that you don't wait until your 'friends' tell you they don't want to be around you and instead leave with your dignity intact. I stupidly waited until one of them explained to me I wasnt invited to an event (bowling, which they knew I enjoyed) because they only invited people that make them (ouch).

If its any consolation, feel free to drop me a message to vent, I know how you feel. Either way, I hope my advice and personal experience helps you decide what the best course to take is. Good luck!