Cranking husband

I'm really struggling at the moment. I have been married to my husband now for coming up to 6 months. I have taken on his 10 year old son full time and do everything for him. I work full time as a nurse and I'm 5 months pregnant with our first child together. I spend all the time I have with him and I love it. We are a happy little family together. I have started on a new ward and made friends with another pregnant nurse we text each other often in the evenings about pregnancy and work, she often wants to get together. My husband has confessed that he doesn't like this as I should be focusing on him. While we were out today this work friend text me and ask what we were doing. I said she was welcome to join us at the skate ramp. My husband had gone to get water when my work friend and her partner arrived. When Adam returned I introduced him and then Adam sat to the side of me with his back to me. While I chatted to them I put my hand on Adams knee several times and he pushed me away. Later he told me he was upset because he want to spend time with me alone without others. I spent have spent every waking minutes with him this weekend as I usually do. I rarely see anyone except my parents out of work. This morning after being on the beach for his sons nippers, he told me he was upset that I was so able to talk to the other parents and was upset I did cover up more. I'm visbly pregnant and wear a wedding ring. This is very difficult. I feel it's healthy to have others in my life and wish he would realise I'm not going anywhere. He says he doesn't trust me because of previous experiences with other women. I am married to him, pregnant with his child and when he is at work and I'm not I'm looking after his 10 year old son.