"Be Careful, It's My Heart" lyrics

Be careful, it's my heart, it's not my watch you're holding, it's my heart.
It's not the note that I sent you that you quickly burn,
It's not a book I lent you that you never return.
Remember, it's my heart,. the heart with which so willingly I part
It's yours to take, to keep or break, but please, before you start,
Be careful, it's my heart.