I struggle with my self image often...It's getting better with prayer, study and time, but I do still feel it sometimes yet. What I do to keep my esteem up, is I post Encouraging Bible Verses all over the place....to the point at one time that my husband thought I would completely cover the bathroom mirror. I don't have nearly as many on the mirror now, but at the time that was what I needed.
I have two favorite verses that helps me often.....Ephesians 2:10 says you are God's masterpiece. His workmanship. That is one powerful verse when we consider ALL the totally amazing things God created.....Mountains, Streams with waterfalls, springtime flowers, gardens, my children's smiles....and above all that, God calls little ol' me His masterpiece!
Another verse that helps me not stress, especially when the rejection is work related, is Isaiah 40:31 They that wait upon the Lord shall renew their strength. They shall mount up with wings as the eagles. They shall run and not be weary; they shall walk and not faint.
This verse is beautifully dual. The word "wait" can mean more than one thing. On one hand it means to "be patient"...like waiting for a bus. On the other hand it could mean to "serve"...like waiting on tables in a restaurant.
One last thing I have learned over time is part of the basis of needing God is realizing that ALL humans will disappoint or hurt us, but God never will. When I started putting my self worth and joy into God's hands where it belongs, I started to not get offended by rejection nearly as much and over time it's gotten so much easier. Who cares if Joe Schmo thinks I'm not enough.....God the creator of all KNOWS I am perfect in Him (Matt 5:48) and that with Him I can do ALL things (Phillippians 4:13)
Other verses that might help are:
2Timothy 1:7 For God hath not given us the spirit of fear; but of power, and of love, and of a sound mind. (self esteem is a necessary for a sound mind)
1 John 4:4 Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world.
Philippians 4:19 And my God will supply every need of yours according to his riches in glory in Christ Jesus. (self esteem is a need)
Last but not least.....if someone says something to me that really hurts or angers me....I get physical...not with the person, but I jump rope, punch the water bag, work in the garden, scrub the kitchen floor.....whatever it takes to get my heart racing and endorphin to release. Exercise releases endorphin. Endorphin makes us happy. God gave us a very intricate body where all the systems work together....if your mind is out of sorts the rest of you isn't far behind and vice versa. I hope this helps.
Peace!!