mistaken/mistakenly thought

[Pidginboy]

I have mistakenly thought that she was peeking at me.
I have mistaken that she was peeking at me.

Do both mean the same?
Do tenses in first and second part of first sentence agree, Please?

 

[mariajosefigueroa]

to my mind the first option means not understanding
the second one means to think it in a wrong way