So your b/f wants you to move down to Kent and live with him? Do you feel that it would be appropriate to move down there at this current time with the way your other friend is acting? Moving may cause more complications. However, is it possible for your b/f to actually come up to Manchester and live with you (that is if you want him to) ? This would be a better option as you will both be away from your friend and this will allow your relationship to be abit easier going.

I do hope all turns out for the best.