Help :(

How do you get over seeing an ex with someone new and prettier then you. He kind of picked her over me and I just don't know how to deal with that and seeing pi you're of her in his sweatshirt and I don't want to in follow them on social media because I want to know but it just hurts so bad and I throe IP and get sick, I know it sounds like I am over reacting but we were together for 2 years and she is on the sluttier side so I am just worried about them doing sexual stuff... I just can't get it out if my head.