In the state of Colorado, if I signed a lease & never asked for a copy of it back w/ his signature on it is it binding?
The problem is my original landlord lost the property in a divorce to his ex wife, she wants us out so she can get more rent. We have never been late on a payment & are not in default we have 18 months left on the lease. I signed & sent to him but have no copy of the lease w/ his signature. Do I have a binding lease or not?

There are two issues here.
The first is state law re transfer of owners. The new owner does have to honor a lease.
The second is the missing lease. Without now getting a copy from the ex husband, you can't prove it ever existed, and saying it did isn't enough.
You then become a tenant at will, and can be given 30 days notice to vacate.

Where the "owner" and his wife married when you did the lease. Who at the recorder of deed was the owner at the time of the lease, for him to lose it, my guess is that both names were on the deed at that time.

Next even if he "lost it" until she does a refi and pays off the loan on the property ( assuming there is a loan) his name is most likely still on the deed also.

I will disgree merely a transfer or sale of a property does not end the lease, so your lease is still valid.

Now the issue is proving the lease, You will have to argue you never got a copy or contact the husband who lost the home to see if he will send you a copy.

I believe the house was his during the marriage, he acquired it before they got married. I have contacted him about sending me a signed copy, he said he didn't want to be in the middle
Of it.is there anything I can do legally?
I have received a notice to quit by her & have been given 90 days to move out on zero grounds. I also have emails to & from him since the lease was signed & he's been cashing checks regularly since Jan. which is when we signed the new lease. An I totally screwed?

Yes, explain to him that you may sue him for any loss you have, due to eviction if he does not provide you a copy of this. That should get his attention. ** not saying you really have a case against him but he does not know that.

... I have contacted him about sending me a signed copy, he said he didn't want to be in the middle
of it.
...
An I totally screwed?

Not totally.

The fact that he has been cashing checks regularly doesn't mean anything: it would be consistent with a month-to-month tenancy at will. But if she sues you for eviction, you can subpoena him. Use a subpoena duces tecum, requiring him to bring specified documents with him, including the lease. Then put him on the witness stand and force him to admit that he and you signed a written lease.

In fact you can take his deposition now, if you want, in order to obtain a copy; give you peace of mind; and head off an eviction suit 90 days from now. Most jurisdictions allow for depositions in anticipation of litigation. Ask an attorney in your jurisdicition. It's not a commonly used procedure so some attorneys might not know about it, but it's probably available.