Need help with being insecure?

i was with my ex for 4 yrs and he finished it with me for no reason really and he moved on very quickly which made me move on quicky to. I am now with a bloke which i have been with for about a year and a half. Lately i feel so insecure around him. He lives with a house mate and he has a girlfriend. i keeo thinking my boyfriend likes her. My bfriend is 27 she is 18. But he allways seems to be interested in her . He never used to b like that with her. and he allways seems to be looking at her. I dont no if theres anything in it but its making me moody with him. He doesnt no im insecure and i dont really wanna say anything to him. HELPPPPPPPPPPPPPPPP now every little think he says to her i seem to be izing! he did say the otha day she has an attitude, n he would neva spk to her if she wasnt with his mate. But the other nite she went to bed n he said "ah your going bed are you" she was like yeah im tierd got college tomorrow. he was like"oh ok" i was thinking SO WHAT IF SHE GOES BED grrrrrrrrrrr xx