So paranoid hes cheating on me?

We've known each other years and hes always striked me as a good guy.. And we've liked each other for years as well. We have recently decided to start dating each other and im stoked about that...but im very scared because he sent a winky face to a girl mate and called her cheeky...he said that thats how he speaks to his friends...and told me her name and said that she has a boyfriend...if this is the case i feel terrible for even thinking he was flirting or cheating...but i feel really sad about it still....Why do i feel so paranoid and scared about this :( he said that he would stop talking to girls if i wanted but i said i dont wanna be one of those girlfriends who are insecure enough to choose who he talks to...He also likes those pictures of half naked tattoo'd girls on facebook (like public pages)...Im really paranoid he is just going to hurt me..why do i feel like this