How can I make things better

My boyfriend and I have been together for 6 years. Like any relationship its been good and bad. At the very start of the relationship (a few days in) I stupidly kissed someone. I won't go into the reasons behind it because that's a whole other post! But I never told my boyfriend until recently. We've gone through a lot in our relationship and always stuck together. Always everyday we'd say I love you, either by txt while at work or just before going to sleep. We've had 2 miscarriages but have since been blessed with our 6 month old baby girl. In June this year we had a bad argument where I told him about that kiss all those years ago. Understandably things have changed. Part of the reason I kissed someone was because he was messaging someone else arranging to meet up. But he doesn't see that's wrong too. I've taken full responsibility for what I did and I'm doing all I can to make it right. I know he loves me because I know he wouldn't be with me if he didn't. I still tell him all the time I live him, just like I used to but I get nothing back. Yet when he talks about future things he says 'us' so it's like he sees a future for us still but there's no affection. No cuddles unless I make the first move, no kisses. I just miss the little things. How can I get it back. I've tried talking to him but he just closes up. He won't talk about feelings and relationship stuff