Sorry to read about your unfortunate turn of events. Regardless of what course of action you decide to take, in your situation I would seek out to find out as

Sorry to read about your unfortunate turn of events. Regardless of what course of action you decide to take, in your situation I would seek out to find out as much as possible about the staffing, investors, connections of your competitor. If you have the funds, I would suggest hiring a PI to get as much information on your suspected founder. You could also file FOI requests on the government R&D body about the reviewers, their connections, etc, etc. Depending on which country you are based in, there might be an option of talking to possible litigation funders. Information is power, so the more information you can acquire and the stronger the basis you will have for making unemotional decisions. Situations like this are asymmetrical. You don't engage on the lawsuits level but turn up the heat and the risk of public disclosure not only to the competitor but the connections that may have played a supporting role.