And I'm not a lawyer, either, so this isn't legal advice. However . . . .
Regarding the validity of your lease (and thus your obligations and those of the owner or the owner's representative) It's totally irrelevant whether your landlord committed forgery.
The questions are: (1) Do you have a valid lease? And (2) Are you and the owner in compliance with the lease?
You need a lawyer to sort out the issues, and to focus on the relevant facts.
We've talked about this ever-developing story before. I know you are not in great shape to hire an attorney. Perhaps there is a legal aid organization in your area. I'd also check with a large law firm to see if they would give you some pro bono support. I really think you might need legal counsel at this point.
This is not legal advice. I am not licensed to give such advice. However, I will make these observations:
1. Just who is taking your to court? A complaint had to be filed. If it is not the real owner, they may not have standing to initiate a complaint.
2. If you paid an imposter and now the real owner demands payment all over again, they may be entitled to receiving it, if they were completely innocent of the affair. On the other hand, since this guy has a long history of some sort with the real owner, it may be that the owner allowed you to think that he was collecting for her. Then it will be a matter of proofs and other corroborating evidence.
3. If you have not paid the rent for some time, you will probably find that, mitigating stories or not, state laws will force you to leave the property.
4. If you have a good relationship with the real owner (and that's questionable, since she may be the one taking you to court,) you may be able to negotiate a deal where past rent is forgiven if you start paying immediately and perhaps accept a small increase, if you can afford it. In this situation, the owner can only lose even more money by kicking you out, refurbishing the property and searching for a suitable tenant with a good financial position. After all, the owner will not want to get another tenant who will not pay the rent. That would just compound her problems.
5. No matter where all this stands, no matter who said what to whom, no matter "who shot John," it looks that at best you have a very shaky tenancy. The real owner may be stripped of ready cash and not be able to keep up the property and pay a mortgage, if she has one. If she loses the place and you do not have a lease, the lender may force you out quickly. I know there are laws on the books protecting tenants but I also know that there are limits to what a tenant can do to stay in a property. Therefore, it may be wise to start looking for a new place to live. I know you don't want to. I know that you have kids in schools you want to have them going to. I guess that you may find it difficult to find a place that offers what you need on your budget. Nevertheless, it would be better to search without an eviction on your record and without the added pressure of being out on the street in a week or two, which will certainly be the case if all this goes down badly and you have not got your ducks in row before it does.
Wish I could help in a more concrete way but I cannot represent you in legal affairs and I do not work in your area.
You need a Real Estate Attorney to investigate, document, and verify these allegations.