I feel like talking to my ex but he already has a girlfriend...?

i broke up with him last year...after quite some time hmm i guess this year, he got a new gf. But i'm single juz for info (not that i'm jealous or anything)... i juz feel like talking to him all of a sudden...we rarely talk..the last time i talked to him was via fb like a month ago...and the conversation went pretty well i guess...so why do i feel that way? And to add on, i added his current gf on fb cos my fren is a mutual fren but she kinda ignored my request i guess like what on earth... i don't have anything against her neither does she...she doesn't have to be so insecure....oh and the last time my ex and i talked (via fb) was actually a wall post kinda thing (the one with many qns like where i first met u, what was my first impression abt u, etc), he said beautifully smart...(hmm not that i'm flattered, i'm just trying to portray the situation to the best of my ability) so yes, i need to know why i feel that way....thank you so much for your time