Here is something that has stuck out to me-
1/28/14- SM texts TM's sister to check on TM & kids.. Also says "I know you are her sister and I f'd her over".
This appears to refer to his affair with HE. His f'ing her over could refer to his decision to leave her and choose Heather.
But TM has apparently taken her kids to her sister's house and goes on a drinking binge. The affair isn't news to TM, it's been "over" for three months and TM's texts to HE, along her handcuffing him/taking his phone/accompanying him to work are proof of this.
2/2/14 SM texts TM- "I admit I made a horrible choice choosing someone that was



*ed up but I think I can change both of our future together and for the better..."
In the 2/2 text there's a possibility of some syntactic ambiguity. He could be saying he made a horrible choice by choosing to cheat on TM with an unstable individual. "I chose to cheat on you with a girl that was crazy", OR he could be saying he's sorry for choosing HE over TM when she gave him an ultimatum- "I'm sorry for choosing someone, that was f'd up. But I think I can make things better between us."
Not that this solves anything, but just something to consider..