If he makes any call its so HE can get something from it... he isn't going to make that call for YOU. It's the sociopathy.. he's admitted it outright already, if he makes an exchange of any sort with anyone its so HE gets soemthing from it.
If he calls to apologize its so HE can look better to you... he's not apologizing because he's sympathetic... He is apologizing to charm you again.
In my opinion him calling or texting to say "I'm sorry" is just an insult... Actions are the only tolerable apology.. an action of turfing her arse permenently and making an effort to get himself some much needed treatment... THAT is an apology... anything less than that is NOT worth picking up.
This is the problem with addiction, sociopathy, and many other emotional illnesses - when you PICK UP the PHONE you ENABLE them... you cater to the drama and you allow the CYCLE to continue.
No pick up means "NO MORE"... No pick up mean's "DO SOMETHING DIFFERENT I AIN'T YOUR FOOL ANYMORE"
If he makes any call or text its not for you.. he has an illness and he needs treatment for it. Even that last convo you had with him you posted.. he admitted at the end of it that HE FEELS better after having talked with you... That's why he does it... to make HIM feel better.
Do you want to pick up his call to make HIM FEEL BETTER?
Sure, it might make YOU feel better now, but it also enables him and allows the cycle to continue.. its your dynamic with him. He uses you and calls you to charm his way back in and you PICK UP. Don't PICK UP.
Ask your father, I am pretty sure he'll say the same thing - don't enable him any further. The only way to NOT enable a sociopath is to SHUT them OUT.
HE will learn and grow MORE from you NOT contacting him than from picking the phone up. When HE calls and YOU pick up, he learns nothing and does NOT grow an inch emotinoally.
BREAK the pattern and REJECT ANY ATTEMPT at communication.
Re the post earlier, if you can file for child support DO IT. Let a lawyer talk to him instead.