tense - I worked, I've worked, I have been working. I need some clarifications

Could you help me with these sentences:

1. I lied to her. (I'm just making a statment)


2. I've lied to her because the truth would have hurted her.

Second example:

1. I have been working at Google for 10years. (Meaning I am still working there)


2. I've worked at Google and it was nice.(I don't work anymore)


3. I worked at Google. (Not sure about the difference with the previous one)

I'm learning the different tenses and it isn't so easy for me. Any help would be welcome.

Regards,