Thank you letter

My attempt here is to write a 'thank you' letter for my manager who is leaving the company next month. Could you please check the letter for any grammatical errors?

XX,
I was little bit surprised when I heard the news from you during the meeting yesterday.

I have been proud to be a part of your team. Your exceptional leadership and the time management skills are inspirational. You are the one of the best managers I have ever seen.

Thank you for your guidance, support and excellent management. I wish you all the very success for your personal and professional career.

Please accept my apologies for the mistakes I have made. The short tenure that I have worked under you is the best period of my career so far.

We(company name) will miss you surely.

Thanking you,
YYY