My ex.... 😥

So my ex and I broke up like 3 or 4 years ago! But last year we started talking again and kissed,cuddled... you get the point... but in the past 2 months he has a girlfriend now (he’s been with her awhile now) and all I can do is cry. I can’t stop thinking about my ex. Last night I dreamed about me and him.. I also dreamed about his current girlfriend talking to me. I don’t know what to do. I feel sick to my stomach just knowing he’s with her. I can’t stop crying, please help me. 😥😥😥😥