Should i go on this trip without him?

So my bf of 4 yrs and i had decided to have a ldr(he is going to study abroad) but broke up bc he says it is impossible to keepp a ldr for 5 yrs.Anyway we are in the same class and we have this 3-day trip this weekend.He cant come and we had decided to go on a weekend later just the 2 of us.Now that he left we what should i do?I dont want to look like i am having fun(bc i know i wont)and i want him back.What to do?heeelp