Oh man...I am so sorry to hear that your step children would mistreat you so! :( As if the situation wasn't tragic enough...this saddens me greatly. You did not deserve that....and I am sending my sympathy for the further hurt you have endured. However, I am so proud of you for getting representation for yourself and fighting back for what you needed!! Well done, you!
As far as the positive mantras go...it depends on what negative thoughts you may be struggling with. For me, my fears center around health, or having some kind of disease, condition, episode...so I use this one often when I am challenged with physical symptoms:
"I am okay, this is only anxiety making me feels these things, and nothing health related."Basically, you want to speak in contradiction to the fear.
Here is a great link that explains this technique more in detail, and will give you more ideas.:)
Positive Mantra/Affirmations for Anxiety Managementanxietynetwork.com/content/coping-statements-anxietyHugs and high fives,
S.C.