As you have explained the situation, the company that drilled the new well did so without a valid lease and without the consent of the lessee that owned the valid lease. This assumes of course that the lease you signed was validly recorded, executed and you in fact own the mineral rights where the well was drilled. This sort of situation is un-common, but not completely unheard of. If these facts are correct, the company that drilled the well has committed trespass on the lease. Any reputable operator conducts a drilling title opinion prior to commencing operations to drill a well in order to prevent this exact thing from happening. The title opinion is done by an attorney and lists any and all title defects that may exist. These defects are then normally corrected prior to drilling operations. In this case, if the company that drilled the well did so without a title opinion, a strong case can be made for bad faith trespass. . If the valid lessee can prove that the trespass was on purpose or done in bad faith, the company that drilled the well could be required to turn over the well and all production to the valid lessee as well as make restitution for any reserves already produced. If bad faith cannot be proven (i.e. the well was drilled with a title opinion that was in error) the company that drilled the well can be allowed to recoup their costs of drilling, but beyond that the valid lessee would own any production. The valid lessee could possibly require the trespassing company plug the well if the costs to operate the well going forward exceed the value of the reserves. This or course will effect whether or not your lease is HBP in the future.
As to the lessor, a lot depends of the facts of the case and what settlement, if any, the valid lessee wants to pursue. At minimum, you would be entitled to your royalty under the lease you signed as well as any damages to the surface if you were the surface owner. If I were in your situation, I would request a written statement of the facts surrounding the drilling of the well from both companies and then evaluate your options.