"Get over it" versus "Get it over with"

English as a Second Language English Vocabulary, Grammar and Idioms
1

Hi

Could you please tell me the difference between the following?

1-“Get over it”
2-“Get it over with”

Tom

2

Hi Tom

dictionary.reference.com/browse/get%20over (scroll down to defintion 47)

dictionary.reference.com/browse/over%20with (scroll down to “over with”)

Amy