K.B.
My son's dad and I were never married, but we did live together for a short time (from the time my son was 1 and half to almost 3). When his dad moved, his dad let him "help pick a new place to live". He asked my son for approval of everything. We explained to my son that he would live with me and his dad would live with his new friend (girlfriend) at their place. We told my son that we all loved him very much and he could sleep or visit dad whenever he wanted. I think the biggest thing that helped my son adjust is that my son's dad and I have NEVER once yelled or argued in front of my son. We come up with choices and then allow my son to choose so he feels a apart of it all. I mean the choices would be like "You are going to spend time with Daddy. Would you like to spend the night there or would you rather come home at bedtime?" Gratefully I have a child that adjust rather easily and quickly to change. When I put him to bed at night, we review tomorrows plans and if he's at his Dad's I call and give him time reference when he will be coming home. Knowing what is going to happen and when helps them too I have found. IF you CAN without arguing, maybe you can still do some small things together. Such as going out to dinner one night a week and try to celebrate holiday's together. We try to look at it as our family is just bigger and more spread out now rather than broken. I'm not sure your situation, but maybe this will help.