My best friend keeps touching me?

my best friend is a guy. we've known eachother ever since we were about ten or eleven, and i used to have the biggest crush on him. everybody knew about it too. but it ended when i was about thirteen cuz i overheard him talking with one of his buddies. his friend said something like, "When are you gonna ask brittany out? you know she likes you." my friend says, "yeah, i know she does, but i just like her as a friend. she's kind of ugly to me." i was completely heartbroken. i couldn't help but burst into tears. they overheard me crying and my friend ran out to comfort me. he apologized about a thousand times and really did seem sincere. i know he didn't mean to hurt me, but he did mean what he said. we're both eighteen now. he used to have the BIGGEST crush on my sister, Pamela, who is the exact opposite of me. she's gorgeous. she has big boobs, a big butt, great curves, and a pretty face. i have really low self-esteem now, and i think i'm ugly. unfortunately, i'm a redhead. he says he's gotten over her. "I don't even know why i ever liked her," he sometimes says with a grimace. he tells me he thinks she's ugly. i think he's just saying that. lately, he's been acting really weird around me. he keeps touching me. not inappropriately, but out of nowhere, he'll randomly run his fingers down my arms. sometimes, he comes up from behind me and gives me the biggest hugs, and starts touching and squeezing my sides and my stomache. i like to give him lots of kisses on the cheek, cuz i'm just very loving towards him. he usually gets annoyed when i do that, but recently, i did it, and he held my face there and told me to keep doing it. then another time, he turned his head and started kissing me on the lips. i freaked out, and tried to push him off, but he's too strong. he held me tight and started kissing me all over my face. and yesterday, he said something that REALLY shocked me. he told my i'm pretty. he's NEVER said that before, EVER!!!! i was speechless. i don't think he actually thinks i'm pretty, but it's weird that he'd even say it. maybe he's trying to heighten my self-esteem. i'm really confused. why is he acting this way? does he feel guilty? i'm too embarrassed to ask him. please help. sorry this is so long.