Sorry about your wife's health issues. In any case none of us can tell you what makes sense. I can start by pointing out some serious considerations.
If you decide to sell the house, you will probably be faced with some major issues. It is hard to get rid of a house full of stuff. You can compromise by packing up a little or a lot and sending it to storage. Be aware that storage costs become very significant after months or years. Dealing with that stuff in storage is more difficult than dealing with it now.
You need to consider your hobbies, interests, lifestyle. There are a lot of activities and lifestyle choices that do not fit with RV living.
Are you interested in travel and visiting places such as National Parks or are you just looking for a cheap place to live and will spend most of the time in one or two areas?
To answer one question, you can spend a little or a lot with RV living. Many RV parks and campgrounds with hookups are expensive and getting more expensive by the year. In many areas of the country suitable places for long term camping are in short supply. There are plenty of places to live at very low cost. That would include National Parks, Forests, etc. You will need to move frequently because of limitations of duration of stay. You also need to consider getting a solar system and getting away from the need for hookups.
If you are going to sell the house and do even minimal interState traveling you will need to make logistical arrangements: mail, banking, medical providers, choice of State of residency, etc, etc. Do the research and decision making in advance.
You have been given advice on proceeding slowly. Maybe but you also are not getting any younger. If you want the mobility and travel allowed with an RV you might want to proceed quickly. Only you know yourself. Don't make a choice that you are likely to regret.