There is a difference between keeping secrets and holding something private. While keeping secrets is unhealthy, I agree that it is not only ok, but healthy for married partners to have things they hold private from one another.
But this feels like it is no longer about privacy because she knows about it and has specifically asked you to stop. It may be that her reasons are rational: your size might be perfect for her and more girth might make sex less pleasurable, etc. Or her reasons might be irrational: concerned that you are too involved in a semi-erotic habit fixated on making your penis larger which could feel threatening to her in case it makes you wander toward other women, etc. Or some combination of rational and irrational.
But the unfortunate reality is that she has directly asked you to stop and went so far as to trash your equipment. To me there are only two ways forward that respect the marriage relationship:
1. You tell her that you understand her feelings but still want to engage. In this case you might try to convince her that she has nothing to fear, it isn’t a deviant practice and that her agreement is supporting something you feel is somewhat important. Depending on how skilled you are as a couple in conflict resolution, perhaps couples counseling is in order since the dynamic of the conflict and doing things like throwing away your device seems a little extreme, as does your insistence that you want to have a penis size she isn’t interested in. A counselor might help you deal with this issue in particular and help heal whatever dynamic is at work that is bigger than just the conflict over pumping.
2. You let it go and stop PE because the conflict with your wife is not worth it. After all, PE is best when it results in both partners enjoying your penis. If that isn’t the case, then why do it? Plus you already have a large penis. Even if her resistance is irrational, it is not a hill worth dying on in terms of a happy marriage.
If you continue in secret and she finds it again you will probably regret it since you will have gone from a privacy issue to a secrecy issue, and secrecy is toxic to a marriage, and continuing on without telling her is essentially lying.