Problem in paradise

Me and my ex boyfriends was together for 8months we separated last month I recently moved in becaus family issues and now we're haveing sex again and we both get mad wen we talk to watch other people but we won't get back together again because we we know it's just gonna be the same shit over again so we call what we're doing an understanding but he keeps freely nutting in me and I don't know if that's okay because I could get pregnant and that make bigger problems u know