Joe, brother, I am praying for you, your sister, and your sister's boyfriend's daughter.
I have greatly struggled with the anger too so I know how difficult it can be and can only imagine how much more in a time like the one you're experiencing now.
You did the right thing to follow the Holy Spirit's prompting to seek the Lord about it, God's grace for your thoughts, and prayer for those hurt in the shooting.
Psalm 73:28 But it is good for me to draw near to God: I have put my trust in the Lord GOD, that I may declare all thy works.
1st Peter Chapter 5: verse 7
Cast all your care upon him; for he cares for you.
1st John Chapter 5: verses 14 and 15 assure us:
And this is the confidence that we have in him, that, if we ask any thing according to his will, he hears us:
And if we know that he hears us, whatsoever we ask, we know that we have the petitions that we desired of him.
Romans 12:19 says Dearly Beloved, avenge not yourselves, but rather give place to wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.
Isaiah 26:3 Thou wilt keep him in perfect peace, whose mind is stayed on thee: because he trusts in thee.
Philippians 4:4-8
Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God.
And the peace of God, which passes all understanding, shall keep your hearts and minds through Christ Jesus.
Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things.
Exodus 33:14 And he said, My presence shall go with thee, and I will give thee rest.
Isaiah 53:4 and 5
4 Surely he hath borne our griefs, and carried our sorrows: yet we did esteem him stricken, smitten of God, and afflicted.
5 But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.
Jeremiah 17:14 Heal me, O Lord, and I shall be healed; save me, and I shall be saved: for thou art my praise.
Jeremiah 30:17 For I will restore health unto thee, and I will heal thee of thy wounds, saith the Lord; because they called thee an Outcast, saying, This is Zion, whom no man seeketh after.
Isaiah 55:6
Seek ye the Lord while he may be found, call ye upon him while he is near.
Isaiah 41:10 Fear thou not; for I am with thee: be not dismayed; for I am thy God: I will strengthen thee; yea, I will help thee; yea, I will uphold thee with the right hand of my righteousness.
Jeremiah 31:3
The LORD hath appeared of old unto me, saying, Yea, I have loved thee with an everlasting love: therefore with lovingkindness have I drawn thee.
Joe, may the Lord quicken you by His spirit and give you comfort, grace and peace to sustain you now and always in the love of God in the name of Jesus. May the Lord Himself bless your sister and the other woman shot with full healing and restoration of health in the name of Jesus. May His peace comfort those who are grieving and bless all those who call upon His name with the peace that passes all understanding. Amen.