Universe question

Delete TikTok, it's not good for you!

That video is absolute horsepoop. The Mandela Effect is nothing more than people misremembering things.

I question myself „Is my husband really my husband I met years ago?“

Not really a physics question, more a question of neuroscience and psychology, or even biology in general. Fact is that who someone is is a product of their genes and their environment, the latter of which provides input that's continuously changing to varying degrees. Some people can remain more or less the same person they were decades ago, while others might have a radically transformative experience and become an entirely different person overnight, but there's always going to be some level of change throughout life.

If you think about it, consider that your husband at some point didn't exist at all, and at some point is going to die, and that everything in between is a state of continuous transformation (to smaller and larger extents). The idea of your husband as some static and unchanging thing seems rather strange to me, and would be at odds with how life works.

I watched the link. 

It's pseudoscience quackery. Total garbage, not grounded in any actual science. 

So I'm not willing to look at the video because I'm not willing to watch TikTok, but hopefully I've got a sense of what's going on from your question. And this conversation predates science so it's not really physics related. It's more of a philosophy thing. But...

There's a concept called causal reasoning, the relationship between cause and effect. The easiest and fastest way to get the idea is with physics and force. If I apply force to a wheeled cart by pushing on it, the energy I apply will cause the cart to move. Because of universal laws, I can also expect that the cart will move in a direction that's a long the same line as the force I'm applying (push forward, cart moves forward). By the same token, if I apply a new force to an existing system, I can change an effect currently in process. So if a leg is holding up a table and I apply a sideways force to the leg by kicking it, the leg will break or fall. Since the leg is no longer applying upward force to the table, which it has to to counteract gravity, the table will fall. Basically, every effect has a (or multiple) cause and every cause has an (or multiple) effect.

Now let's assume that you are hopping between universes named A and B. You could apply a force to our wheeled cart in Universe A, then jump to Universe B. There's no reason to think the cart would be moving in Universe B because the force was applied in Universe A. No cause would necessarily be present in the new reality to create the effect of the moving cart. It gets worse because there's no reason given why anything would be the same in Universe B as in A because causes and effect build on each other. You chose to push on the cart, but what cause created the effect of you deciding to push on the cart? What cause created that cause, and so on and so forth all the way back to the start of the universe. If you've hopped universes, your pushed cart could move to the left instead of away from your push, or the sky could be green, or the planet Earth could be gone and you're left floating in open space, or the fundamental forces of the universe could function completely differently. Changing universes could mean that things are only slightly different, but it would be just as likely that there would be massive changes that you would clearly see.

Since we don't see that happening, that any given cause results in predictable effects rather than pure randomness, we can pretty safely dismiss the idea that we are moving between universes on a regular basis. Fear not, the pile of atoms and molecules that make up your husband are the same as the ones that were there yesterday.