Hopefully you get the water and power issues resolved quickly! Since you are mobile, perhaps you can get to someplace with temperate weather? At least that way you would be in less danger of freezing.
How long were you two planning to RV? Is your search for a smaller place in one area in particular, or is the idea to travel around the country?
This grief journey is tough, and the path for each of us is different; but it seems there isn't much that someone on this site doesn't share with you. Draw on the group to help you cope. I was in a total fog for the longest time. I am fortunate that our kids live nearby and remain in constant touch. Also I stumbled onto Bereaved Spouses, which showed me I wasn't alone - the folks here know first-hand what it is like to have your world collapse. Sharing helps.