Imitation of Christ:
"The Eighth Chapter
SELF-ABASEMENT IN THE SIGHT OF GOD
I WILL speak to my Lord, I who am but dust and ashes. If I consider myself anything more than this, behold You stand against me, and my sins bear witness to the truth which I cannot contradict. If I abase myself, however, if I humble myself to nothingness, if I shrink from all self-esteem and account myself as the dust which I am, Your grace will favor me, Your light will enshroud my heart, and all self-esteem, no matter how little, will sink in the depths of my nothingness to perish forever.
It is there You show me to myself -- what I am, what I have been, and what I am coming to; for I am nothing and I did not know it. Left to myself, I am nothing but total weakness. But if You look upon me for an instant, I am at once made strong and filled with new joy. Great wonder it is that I, who of my own weight always sink to the depths, am so suddenly lifted up, and so graciously embraced by You.
It is Your love that does this, graciously upholding me, supporting me in so many necessities, guarding me from so many grave dangers, and snatching me, as I may truly say, from evils without number. Indeed, by loving myself badly I lost myself; by seeking only You and by truly loving You I have found both myself and You, and by that love I have reduced myself more profoundly to nothing. For You, O sweetest Lord, deal with me above all my merits and above all that I dare to hope or ask.
May You be blessed, my God, for although I am unworthy of any benefits, yet Your nobility and infinite goodness never cease to do good even for those who are ungrateful and far from You. Convert us to You, that we may be thankful, humble, and devout, for You are our salvation, our courage, and our strength."
This is a chapter from The Spiritual Combat, dealing with that as well
I really suggest Imitation of Christ by Thomas A Kempis.
Book 2 Chapter 5 p.76, last para:
"Those who love God and their own soul for the love of God despise all else; for only the infinire and eternal God can fill our every need and desure, the solace of our soul and the true joy of our heart."
So, clearly, we are to love ourselves in the sense of what God made us. [Have respect for ourselves etc]
However...book 1 chapter 2 p.18 (last para) states: "Nothing is so beneficial as a true knowledge of ourselves, which produces a wholesome self-contempt. Always think kindly of others, while holding yourself as nothing; this is true wisdom and leads to perfection." -- "Always keep in mind that all are frail, but none so frail as yourself."
I have to go now. God bless