Ex girlfriend's friends are trying to contact me and are attempting to be nice?

Anonymous
background: girlfriend and I broke up in start of 2009. we never spoke since (because of her).

recently a few situations have occurred in which her friends are trying to contact me and be nice. in the start of 09 they wouldn't help me when I tried talking to them and they helped her stay away from me. I don't understand what's going on, please help!

Situation 1:At the end of 09 her best friend tried to re-add on Facebook. 1 day at school her close guy friend said hello and he invited me to hang out with "everyone". the next day @ 11 pm some1 called me with an unknown #

Situation 2: Around NYE I went to a party at a bar. I looked good cause I was working out and dressed well and felt confident. as I walked I noticed my ex and her head was following me. 20 min later her friends came up to me 1 by 1 and back to back, 7 in total. they were her best friend, cousin, close family friend, best guy friend, an old friend of mine, and others. they gave me complements and hugs from the girls, asked me questions about my life (aka school, work, family, friends), they asked for my cell number, and also suggested that I hang out with them and go back to old hangouts. furthermore 1 of the guys tried to get a reaction out of me by bad mouthing her. overall I was very nice and polite to them, but was very shocked that they came over to me. I didn't ask or say and e thing about her to them. while these people spoke her sister and other friend kept walking by but never said hi or even looked. it looked like the ex sent them over. also, I got another call at 11 pm from unknown number next day

Situation 3:at a banquet 1 of her friends walked up to me saying hello. it was her only friend I kept as a friends on Facebook, but the couple times I tried to say hi she never responded. when we saw each other out she never even looked or acknowledge me. this night she walked over and smiled and tried to have small talk. she even brought up the fact that she recently hung out with my X.

Situation 4:last week I met friends at a cafe. there was an open table next to us and my X's friends and sister sat there later! soon enough 2 of their guy friends walked to me and said hi and were trying to talk offering me a cig and drink. as we spoke the sister came and gave me a hug and kiss on the cheek. next, she asked how I am and where I have been hiding. 10 minutes later she left the cafe and said good bye to me while the guys in their group stayed for more drinks. also, one of the guys in the group complemented me saying I looked good and in shape and that it looks like I have been working out. he even said he liked my shirt.

whats going on? why are all her friends trying to be nice to me? why are they all trying to approach me and talk when before they were doing the opposite? does it mean anything that the sister spoke to me? what are these people telling my ex? is my ex involved in any way?

what do you guys think? these are only a fraction of questions I have. the entire break up was strange and these current events are even odder.
Updates
+1 y
what does this girl think when she sees me? for example the night of the party when she looked at me what ran through her head?
Ex girlfriend's friends are trying to contact me and are attempting to be nice?
2 Opinion