I don't know enough about this situation to have really appropriate answer, and I don't think I would learn enough about it without camping out at your house for a few days and seeing the dynamic in action. I can explain what I did with my late wife and hope that it provides you with some useful information.
First, I trusted my late wife implicitly. When you sleep in the same room with someone in a house filled with weapons, you'd better.
Second, virtually every gun I own was purchased during our marriage. Legally, my understanding is that makes them a community property asset, as much her property as mine.
Third, my Plan A was for her to outlive me. Statistically that's usually a safe bet with men and women in later life.
Therefore I kept and still maintain a detailed spreadsheet of my firearms, with serial numbers, dates of purchase, actual purchase prices (including DROS and tax) and a summary of modifications and extras (scopes, magazines, extra components, etc.) associated with each, along with their cost. In a separate PDF file is a set of photographs of each arm. I do separate spreadsheets for longarms and handguns, and include antiques, black powder repros and air guns. As my collection has grown, I've found this recordkeeping useful for my own benefit. I keep a couple of backup copies of this documentation on flash drives.
I showed my wife these lists after I first created them and asked whether she had any questions (reply was whew, that's a lot!) and told her where copies of the files would be stored in case I died and she wanted/needed to liquidate all or part of the collection. I also left instructions on how to open the various safes and which of my friends to consult with when selling firearms to get good deals and remain within the law. She then promptly tabled this whole issue and trusted I would have things up-to-date if it was needed later on. She didn't like thinking about death, and ironically died of cancer at 62, well ahead of schedule.
Having clear documentation, including a separate paper file with all the original purchase receipts and DROS forms is equally useful for insurance purposes, or in the event of police seizure (I'm in CA, so I need to consider this.)
If you are concerned that your spouse has ulterior designs on your firearms or assets in general, I suggest making a list such as this, give your spouse a brief look at it so she knows it exists and what it includes, then make a copy and tell her you have it in your safety deposit box at the bank, where she can find it in the event of your death or incapacitation.
Here is a brief story that may also prove instructional. My shooting buddy had a sister who was married to a gun guy. They divorced after two daughters and years spent together. He later remarried. Both he and his second wife ended up living with one of the aged 50-something daughters in what amounts to end of life home hospice care. Neither could take care of themselves, or manage their finances or healthcare. The daughter was given possession (in writing) of the gun collection and related material (ammo, reloading material, etc.) with the intention to sell everything to help defray the medical bills.
This gun guy did not keep written records of any kind. My buddy and I have been assisting with the identification of the various arms and providing a sense of relative values. Some have been sold locally, some are earmarked for auction sales when time permits, some of the non-regulated material was liquidated at a local gunshow. He had a lot of stuff and the process is still ongoing. Proper purchase documentation would have been a Godsend!