Help?! Feeling jealous is making me miserable.

So I've been with my boyfriend for about a year now, known each other for two. We live together, I realise this may seem a bit soon but we agreed to live together before we become a couple and it's working out well. We never argue and so far it's all been fine. However, for the last five months I've started feel jealous, and although I know it is irrational to feel this way I can't help it and it's making me really anxious.
He's the kind of person that is friends with everyone and has really close friends that are girls, in fact, one of his best and oldest friends is a girl. I was insanely jealous of their friendship, which I thought was fair enough, I mean they used to share a bed while we were together. (I told him I was uncomfortable with this and he was very understanding and didn't do it again). Even though I had this promise I felt very jealous, that was until I met her and realised how their friendship was just like any other friendship he has with guys. So that was fine, the feelings went away, but recently I've started to become jealous of the friendship he and our female housemate have formed. They spend a lot of time alone together chatting and laughing, just like me and him did when we first got together and recently at a party they snuck off together somewhere. Although I don't think anything happened I just can't help but feel uncomfortable with how close they are. I know I need to relax and stop letting these fears get me so down because I know deep down we're great together.
We've briefly spoken about my feelings and because I know I'm being stupid, I try to cut the conversation short, but the truth is it really bothers me.
I'm scared that if these feelings continue I won't be able to contain them and they will end up ruining our relation because he feel as though I'm accusing him.
Any tips on how to banish these thoughts would be greatly appreciated!

So I've been with my boyfriend for about a year now, known each other for two. We live together, I realise this may seem a bit soon but we agreed to live together before we become a couple and it's working out well. We never argue and so far it's all been fine. However, for the last five months I've started feel jealous, and although I know it is irrational to feel this way I can't help it and it's making me really anxious.
He's the kind of person that is friends with everyone and has really close friends that are girls, in fact, one of his best and oldest friends is a girl. I was insanely jealous of their friendship, which I thought was fair enough, I mean they used to share a bed while we were together. (I told him I was uncomfortable with this and he was very understanding and didn't do it again). Even though I had this promise I felt very jealous, that was until I met her and realised how their friendship was just like any other friendship he has with guys. So that was fine, the feelings went away, but recently I've started to become jealous of the friendship he and our female housemate have formed. They spend a lot of time alone together chatting and laughing, just like me and him did when we first got together and recently at a party they snuck off together somewhere. Although I don't think anything happened I just can't help but feel uncomfortable with how close they are. I know I need to relax and stop letting these fears get me so down because I know deep down we're great together.
We've briefly spoken about my feelings and because I know I'm being stupid, I try to cut the conversation short, but the truth is it really bothers me.
I'm scared that if these feelings continue I won't be able to contain them and they will end up ruining our relation because he feel as though I'm accusing him.
Any tips on how to banish these thoughts would be greatly appreciated!