I'm confused....what does he mean???

ok so we've been broken up for about a year and 3 months, he's never said a word to me till today, hes in my science cl and he walked in before me, set his stuff down turned around and waked out and as he walked by me he said hi jessica, but didnt stop, he kept walking. he's been trying to be near me, i think, like as of a week ago he decided he was going to sit at my lunch table with me and my friends and his group followed him, so my friends and i have one half of the table, and his friends and him have the other, the other day he threw his trash away from lunch and came and sat right next to me, but was still talking to his friends,he didn't even acknowledge that i was sitting there, well he kinda did but not really, i was on the end of our half, and we brushed shoulders, he's acting wierd, and when he said my name in science today my stomach flipped, and i looked at him but he had looked away and i tryed to contemplate it, and also when we picked seats in science, he sat down two seats behind me, i dont know what to do, when he said my name he said jessica, but when we were dating he always called me jess, im confused!!!!