Argument with husband

So basically my husband and I got into a huge fight and I couldn't handle it anymore so I went to live with my parents in another city to "cool down" for a few days. It has been about a week and I am still too pissed off to sit and talk and discuss if we will even continue this marriage or not. My problem is with my son, we try to divide it 2 nights with me and 2 nights with his dad but I have never been far away from my son since I am a sahm. I feel bad because he asks all the time why I am not home with them. My heart aches those 2 nights and i don't go out. Should i explain to my 4 year old what's going on? How do I handle being far away from him?