Just speculating, but whenever I look at pictures of Kyron, it occurs to me how much he looks like Desiree.
I don't know if Terri is a competitive person but she certainly took part in body-building competitions. And she is a pretty woman. Once upon a time, when Desiree was ill, she may have "competed" with her for Kaine...and she won.
She won Desiree's husband, her child, everything. Desiree was sick...Terri was healthy and beautiful....very attractive to men.
Time has passed. If she still feels competitive with Desiree...Terri cannot be too happy now. Now Desiree has a seemingly happy marriage and a job and maybe a lot more personal freedom since neither of her children live with her. Maybe Desiree seems (with two incomes) to have more personal money at her disposal. And Desiree is now the stunningly pretty woman.
Terri is now overweight and unhappy. Even her "sext-ing" does not provide productive resulrs. Maybe Kaine doesn't seem like such a prize. She can't get a job. Maybe she sends her son away to gain more freedom herself....like that annoying Desiree has.
But she is still having to put so much time into Kyron, Desiree's son....who looks so much like her. She's stuck with the burden of Kaine and Desiree's child. Kaine will never let her sent HIM away. He irritates her. His non-perfection at school seems to reflect on her...not his Mother. The "perfect teacher" who wants a job...thinks Kyron needs to be perfect too...to show just how excellent Terri is in all matters related to children.
Maybe with her older son gone, Terri fears losing the support money that may have been at her disposal...another infuriating thing. She should have the job she wants like Desiree does! She looks at Desiree and now feels that she who once competed with her and won hands down...is now losing in every category.
This frustrates and infuriates Terri. And now, if all this were not enough, Kyron , the little ingrate, is saying he wants to live with Desiree! How will THIS look at school, to friends, to Kaine? Much as she'd like to get rid of him..it should be her idea, not this ungrateful kid. After all she's done for him!
And look at him! He looks just like her rival...Desiree...who now has the life that she, Terri, wants and deserves....love, freedom, money, great figure, gorgeous looks.
Yes, I can see her snapping. And I can also see her being able to rationalize that everyone ELSE drove her to it.