Your question is essentially about risk, and your job is to weigh the different risks against the potential gains. Of course, there’s the risk that you and your child will be exposed to the coronavirus while traveling to and vacationing in Florida — that risk, according to the CDC, is low. (The risk is low even in communities where the virus is currently spreading, but it is slightly elevated for healthcare providers treating patients with coronavirus and for people traveling to international locations with a wider spread of the virus.) Of course, the situation is changing rapidly and, depending on when your trip is scheduled, the risk for traveling to Florida specifically, or being confined to a small space with others in an airport and airplane, may be higher than it is now, and you will need to re-assess the risk closer to your trip (and pay attention to CDC recommendations for travel).
Besides the risk of exposure to the coronavirus, you risk two other things: resenting your husband if you miss your trip; and his resenting you if you don’t. You have control over the former; you can make a decision based on information provided to you and on your own wisdom, and you can take ownership of that decision. Rather than cancelling the trip to appease your husband, you would decide to cancel the trip only if YOU felt it was the best decision. He might resent you for taking the risk, but the resentment would likely only materialize if you or your son actually were to develop coronavirus. (Again, the risk of that is currently very low, and if you did catch the virus, it might be impossible to prove where you got it.) You can also limit your risk of both exposure to the virus and your husband’s resentment if you communicate about what precautions you plan to take during the trip.
There’s one more potential risk related to your trip: You risk disappointing your kid if you cancel — a risk that is sure to materialize if you do postpone. But kids get disappointed and it’s not the end of the world. (One might even argue that experiencing mild disappointment builds character, especially when guided through healthy ways of coping with said disappointment.) You could do something else fun during the time you’d be in Florida, and you can promise to re-schedule as soon as possible (which may be sooner than you think, possibly).
You asked what I would do in your situation, and it’s impossible to say exactly since I don’t know your husband or your kid or the elderly relatives you live with and can’t appropriately assess the risk that involves them (and I’m speaking most especially about the risk to your relationships as opposed to the risk to their physical health). But I can tell you what I’m doing in my own situation. We – my husband, two kids, and I — have an international trip planned in April (to Mexico, which is not currently on the CDC’s list of countries to avoid). It would be our first international trip in nearly eight years (so the first for my 4-year-old daughter and the first my 8-year-old son would remember) and also a celebration of my husband’s 50th birthday. We’re really looking forward to it and would hate to cancel. But! The trip is still five weeks away and we are resigned to cancelling it if, by then, the risk of exposure — in Mexico, in airports, on planes — is much higher than it is now. We’re paying close attention to the CDC recommendations as well as to updates from our local health department. We will re-evaluate our plans with any change in the risk assessment locally, as well as in Mexico.
In coming weeks, I expect more and more disruptions to daily life for all of us Americans. School cancellations, trip postponements, long lines at grocery stores and pharmacies, price gouging, and halting public transportation are all possible. We may all be called on to make some sacrifices to limit the spread of this virus. If you have a chance to get away before such a call is made, this might be a good opportunity to do so—-but only if the benefits outweigh any risk to your relationships and physical health.
You have two choices if you don’t want your relationship to continue being a long-distance one: You can move to where your boyfriend lives, or you can break up. He’s made it clear through his actions, if not his words, that he has no intention of leaving the town where he lives. He’ll continue telling you what he thinks you want to hear – that he’s always wanted to move back to where you live — but wanting something and actually taking steps to make it happen are two entirely different things. You can’t even be sure he wants what he says he wants, but you CAN be sure of the steps he’s taking, which are to stay put exactly where he is. It’s up to you to decide what YOU want and to take steps to make it happen. If what you want is a relationship that isn’t long-distance, you either move to your boyfriend or break up with him and find someone local.