Should i date this guy?

So this guy messaged me about a month and a half ago maybe two months ago...and we really seem to like eachother he sends me the sweetest texts ever! But one problem is he dated my best friend in 5th grade ...we are now seniors getting out of school, i lost contact with my best friend, since i moved. But every once in awhile we say hey i miss you, the usual stuff old best friends say...but when they dated, they were the cutest couple in the whole 5th grade and in lastested awhile... what to do?!?!