We understand your distress, Donna, and we're here to pray and guide you through this difficult situation. Let's first come before God in prayer:
"Dear Heavenly Father, we come before You in the name of Jesus Christ, lifting up our sister Donna and her cat. Lord, You know the circumstances surrounding her son's heart and the threat he's made against this precious animal. We ask that You soften his heart and fill him with compassion and understanding. We pray that Donna finds a suitable place to live quickly, where she can be reunited with her cat. We also ask that You give her wisdom and guidance in her interactions with her son. In Jesus' name, we pray. Amen."
Donna, it's important to trust in God's timing and provision, as it is written in Psalm 37:5 (WEB), "Commit your way to Yahweh. Trust also in him, and he will do this." Keep praying and seeking God's will in this situation.
Regarding your son, remember that God can change hearts. In Ezekiel 36:26 (WEB), God promises, "A new heart also will I give you, and a new spirit will I put within you. I will take away the stony heart out of your flesh, and I will give you a heart of flesh." Pray fervently for your son, that God may transform his heart.
As you're searching for a place to live, be patient and persistent. Proverbs 3:5-6 (WEB) says, "Trust in Yahweh with all your heart, and don’t lean on your own understanding. In all your ways acknowledge him, and he will direct your paths." God knows your needs, and He will provide in His perfect timing.
It's good that you mentioned Jesus in your request, Donna. It's through His name that we have access to God, as it is written in John 14:6 (WEB), "Jesus said to him, 'I am the way, the truth, and the life. No one comes to the Father, except through me.'" Continue to seek Him and trust in His love and care for you.
Lastly, we encourage you to show love and kindness to your son, even in this difficult situation. In Romans 12:18 (WEB), we're instructed, "If it is possible, as much as it is up to you, be at peace with all men." This doesn't mean you should accept wrong behavior, but rather, strive to maintain a peaceful relationship as far as it depends on you.
Articles:
Welcome! "Therefore welcome one another as Christ has welcomed you, for the glory of God" (Rom 15:7). Trust that God has a purpose for your presence here. Let's stand united in prayer, believing for breakthroughs! 
Joseph Gelli:
Let's lift up @Anonymous's marriage, @Aeruirunmor's missing son, and @Tiffy Taffy's job search. Prayers for peace, safety, and guidance in Jesus' name. 
