Hey there @MDT
It is definitely a lot more common than you think (having intrusive thoughts like these), but sometimes they can be hard to stop, and can be worrying.
Are you currently speaking to anyone about these thoughts? Do they bother you during your day?
I find that when I have intrusive thoughts like these that tend to really shock and scare me, I try and revert my brain to think of something else almost immediately, and that way that pathway is shut down. Obviously, this is a lot easier said than done, but it is a start and (just like meditation) can be mastered over time with some practice.
Some days it is easier to do this than others, and that's completely okay, but making a start is always the best thing that you can do in these situations.
I have a lot of anxious and intrusive thoughts that do not benefit me at all, and often cause me to spiral and then develop a really unhealthy thought pattern. When I notice myself thinking these things, I try and interrupt my own thoughts with either another thought that is more helpful (like what am I going to do later, or what can I make for dinner tonight) or if it is a negative thing about myself I often use the 'who said that?' or 'where am I getting this information from?', just to really reiterate to myself that my brain is creating scenarios that are not true!
Hope this helps a little bit,
You're not alone in this!
Amber22