You are Not Bitter, Because Christ Makes you Better

One other thing that I have learned in my walk in Christ. I would try to get rid of "bad" thoughts or "bad" feelings.

Those thoughts are no longer our thoughts:

"Likewise reckon ye also yourselves to be dead indeed unto sin, but alive unto God through Jesus Christ our Lord." (Romans 6: 11)

We are alive in Christ:

"For ye are dead, and your life is hid with Christ in God.

"When Christ, who is our life, shall appear, then shall ye also appear with him in glory." (Colossians 3: 3-4)

And He lives in us:

"To whom God would make known what is the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory:

"Whom we preach, warning every man, and teaching every man in all wisdom; that we may present every man perfect in Christ Jesus:" (Colossians 1: 27-28)

This same Jesus lives and works in us, too:

"Whereunto I also labour, striving according to his working, which worketh in me mightily. " (Colossians 1: 29)

If you "feel" better, remember that Christ makes us better:

"But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, even as by the Spirit of the Lord." (2 Corinthians 3: 18)

and

"1Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not. 2Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is. 3And every man that hath this hope in him purifieth himself, even as he is pure." (1 John 3: 1-3)

Do not focus on what you have or do not have,  but know and believe that in Christ you have all things, and He will make you better wherever you have lost or  suffered lack.