All of the important information of your experience and education should be presented in a clear, easy to read, businesslike manner in your CV.
You should not summarize the information in your covering letter. The CV is a formal business document, not written in the first person.
However it is the purpose of the covering letter to show your enthusiasm for potentially working for this company. You use the first person here to describe how you feel your qualifications fit the requirements of the job. You express eagerness to meet with the company to discuss the opportunities for employment with that company.
You are not obligated to mention this gap in your covering letter. Personally I have had several gaps in my work history. They are not disguised in my CV (they don't have an emphasis either). Be prepared to discuss these gaps if you are called in for an interview. This is where they will be discussed.
The object of the covering letter/CV is not to get the job!!!
The object of the covering letter/CV is to get the interview!!!
They are advertising your qualifications to potential employers so that they will want to meet you and discuss having you work for their company.