I miss my ex and i dont want too.?

i went to my best friends party , on friday and my ex turned up with his girlfriend . i ddint think much of it until i noticed wherever i went he was there , so on purpose i knew everybody else was having a good time , so i thought id get drunk myself , and i did enjoy myself most of the night , but as i went to the toilet . i was standing out side the cubicles and opposite , near the boys toilets my ex was standing there staring , not giving me the evils so i turned away anyway i went to the dance floor , and my ex was snogging his gf while looking at me , at this point i feel like a knife went through me so i walked off and spoke to some other friends , ive been concentrating on other things in my life but i have thought of him , but i really miss himm and i have only noticed , if we dont talk we also connect throughh eyes, but im finding this hard :/ i need help someone give me advice.