Side bitch

I’m the side bitch😂 so first of all I’m asking for advice not hate so if your gonna be a hating bitch remove yourself.

So I met this guy, yes he made it aware he had a girlfriend but said they hadn’t spoken in over a week and that she had sent photos of her self to other men and had been talking to other men, well we ended up spending the weekend together and sleeping together we had so much fun but it all hit me when yesterday he said his girlfriend was logging into his Facebook and to not reply back otherwise she will catch him out and now I’m realising IM THE SIDE BITCH, he told me they had a massive argument and said ‘ fuck her’ and that he exposed her to his friends since she wanted to show other men her body ( how immature) well anyway he was showing signs of catching feelings about how he wouldn’t see me to next weekend because of my work commitments and showing me so much love and attention and I can’t lie I generally have gotten feelings so quick but I know how horrible it is to do that to another girl we’ve been texting since Sunday and I don’t know like do you think they would break up? I’m confused I would hate to make a long term relationship break up it’s like I’m questioning if she fount out would he just end things with me and say no more about it ? Idk what to do please help