TEXAS: Jessica Simpson is at war with her sister Ashlee -and it’s all over wedding. Jess -who’s planning to tie the knot with fiance Eric Johnson in a lavish bash this spring -is furious that Ashlee is racing to the altar with boyfriend Evan Ross after only a few months of dating. Jessica, 33, and Eric, 34 -parents to 19-month-old daughter Maxwell and 5-month-old son Ace -traveled to Italy in October to scout venues for their planned nuptials. “As soon as Jessica tipped her family off that she and Eric finally carved out some time to marry this spring, Ashlee started planning her own wedding,” said a source.–SH