How do I avoid answering the call of a toxic parent?

I'm very sorry for what you have been going through, pursuing the love of a parent is one of the toughest things to do in life, and my heart goes out to you.

Now, I want to be honest with you. At the beginning of your question you said that your dad was a wonderful parent until he married a woman who changed him completely. I disagree with you, sorry. A truly wonderful parent doesn't change and stops being a good parent. A good parent keeps being a good parent despite the partner he or she might have. Yeah, maybe his wife is not a good person, but if your dad were a good dad he wouldn't have left his wife to influence him and stop being a good dad to you.

So no, first of all, stop being dishonest to you and accept that your dad was and is a crappy parent. This is him, a crappy dad that should have been for you but let you down.

I know that truth hurts, because our parents are supposed to love us no matter what, and show it, however this is not always the case and sometimes they fail. They are human after all.

This is something you do need to work on. Accepting that your dad is a flawed human being that wasnt and isn't the father you wish he were and probably will never be. Is it difficult to accept that? Yes. Is it impossible? No.

It's not impossible once you realise many other people have dealed with this very same situation and they eventually learnt that it's ok to forgive and let go.

You need to eventually forgive your dad for being a bad and weak parent but you also need to let go of the expectation of him ever changing.

You have tried to mend things with him w no results, it's rather masochistic to keep insisting, knowing that causes a drift in your mental health. So with all the pain in your heart you do need to let this go. How? No contact with him. He's not going to change, but you can change the attitude you face this situation with.

You can choose yourself over him. You can choose to keep your mental peace over having to deal w his drama. You can choose not to answer the phone and block his number and move on. You can choose to look for therapy to work on this issue in order to learn coping techniques and heal from this.

You can also choose to occupy your time and create and nurture new bondings w other people that want you in their lives and deserve it.

you can choose aall this i mentioned above, but you do need to choose yourself first.

Hope this helps. And even though i don't know you, I send you a big warm hug.

Reject his calls. cut him off.

just dont answer the phone

If you feel compelled to talk to him, set boundaries. If he says something mean, don't take the bait. Instead say, "I'm hanging up now. We'll talk soon Bye " And then hang up. Even if you're with him, change the subject or leave if he misbehaves. He'll learn. If you can, see a therapist. If you must, ignore him completely.

block the call, change your number & don't give them the new number

How do you handle not answering?

Just don't answer.  It's really that simple. You do not have to take the calls of someone who causes you distress.  You have no obligation to do so.

You sound like you need a therapist if you don't already have one.  If for some reason not answering is difficult for you (I don't know why it would be, since you know the result of having anything to do with this man), you need to work on that with a professional. 

you're an adult now, and you don't have to answer when your father calls. send him a text saying how he makes you feel and that you think he's toxic and you're done with all his drama. and that you'd appreciate it if he didn't contact you for a while.