I am in a similar situation, my boyfriends wife passed away suddenly 4 years ago and left him with 2 young kids under 3. I don't know much about their relationship other than how they meet and how long they were together for, as he doesn't really talk about it or want to, I went though a stage where I asked his family what she was like and tired to get a understanding and idea of what she was like but I think that just made me feel more insecure. He also had picture all around his house of her which initially I could accept but as time went by (we have been together for 6 months) I asked him about maybe taking down a few such as his wedding photo's I explained that I understood his children need to be reminded of there mother, but felt that when we have dinner parties at his place and my friends come that it looked that like he has not moved on (a discussion we had several time when we first got together). In addition to that he would also bring up her name in conversations and at times called me my her name I took this as meaning he had not moved on. We had more discussions and I explained how I felt and turned things around and said how he would feel if I had pictures of my ex all around or mentioned them, and left it at that. He thought about it for a while and then one day he said to me that he had taken down there photo's . From then on he never called me by her name and her name is not longer brought up in conversations unless it was to do with the kids. I understand she will always be a part of our lives and I make sure the kids have pictures of there mum around and spend time with her family.
It is going to be, a on going thing for me to deal with as you come across things out of the blue that you have to think about, such as the other day there was a red purse on the table we had not seen each other for a about a week and I was unsure if I should ask who owned the purse or not. I think how you are feeling, is how I feel and it is difficult to address things that are important to you without offending his wife memory.