Keep in mind that your mom sounds to be mentally ill. There are many, many mental illnesses that range from mild depression and/or anxiety to violent schizophrenia. All of them can be mild or severe like any other disease. My MIL is probably bipolar but was never properly diagnosed and was treated for depression only. She has said horrible, awful things to people that she loves. The problem with people who suffer with mental illnesses is that they don't want to think of themselves as mentally ill and they don't admit they are sick and need medicine. Most people with mental illnesses can be treated with great success once the proper medication is determined. But they don't like taking their medication. <deep sigh> I have learned a lot about this becuase my daughter has been diagnosed with a personality disorder and she had awful moments and sweet loving moments, and then all kinds of stuff inbetween.
So - I've included some verses below which have given me great solace, I also want you to realize that mental illness is real, you can't pray it away, it's a brain chemistry problem and if the proper treatment is established the ill person can have a full and satisfying life that doesn't destroy the loved ones around them. In your mom's more normal moments try to discuss medical attention and keep trying.
In the meantime realize that your mom, like most mentally ill people almost can't help their erratic behavior any more than a diabetic can control their blood sugar by sheer will. You are not a bad person and there's no bad mother lurking in you - you are the child of a person with a serious life-affecting illness. And you need to find a place of peace in your inner being that can only be provided by the Holy Spirit. I'm so glad you're turning to God's word for wisdom, discernment & solace.
Many of these pasasges are from the Psalms written by DAvid. I don't think that's a coincident as many modern biblical scholars perceive David to have suffered from depression and other mental health issues. How wonderful that God gives us an example in His word that's written by someone who understood the place we are in. And David is said to be a man after God's heart! God can use the damaged!
"I love the Lord because He hears my voice and prayer for mercy. I will pray as long as I have breath." Psalm 116:1-2
"The Lord is close to the brokenhearted. He rescues those whose spirits are crushed." Psalm 34:18
"I come to You for protection, O Lord, my God. Save me from my persecutors-rescue me!" Psalm 7:1
"I love you, Lord, You are my strength. The Lord is my rock, my fortress, and my Savior. My God is my rock in whom I find protection. He is my shield, the power that saves me and my place of safety. I called on the Lord, who is worthy of praise, and He saved me from my enemies." Psalm 18:1-3
"For I know the plans I have for you, says the Lord, they are plans for good, not for disaster, to give you a future and a hope." Jeremiah 29:11
So do not fear, for I am with you; do not be dismayed, for I am your God. I will strengthen you and help you; I will uphold you with my righteous right hand. Isaiah 41:10
What, then, shall we say in response to this? If God is for us, who can be against us? Romans 8:31
I will pray for you mama. This is tough for you but you are doing wonderfully and are seeking the right kind of encouragement. You can do it. Oh - and block her texts if you can - or delete them before you even read them. It's not healthy for you.