You can’t directly avoid having thoughts. They will pop up in your head. But you don’t have to respond to them or fear them. They’re just thoughts that come and go, if you let them.

All of what you are describing is pretty much exactly how people usually behave. To be able to let go of thoughts is a skill that can be learned. Just like learning how to keep yourself clean or how to tidy up a room or how to do laundry. Without those skills the stuff is going to pile up and becomes difficult to manage.

I think that there are other people here who would be better at teaching meditation skills (@amatt), but in general, that is what meditation is: to learn how to cope with the mind in a skilful way.