If you told him that you do not want to stay in communiation. He should not.
Unless you have some weakness which you admitted and you mentioned it in
your blue part of sentence. And you do not want to have your father to know about this. (Not sure if your mother knows all the details)
..you had something which you do not want to tell others.
That is fine. He is taking advantage of this and he is totally wrong.
Solution:
1 Confide with your mother.
2 Ask her to tell your father some weirdo is following you…from some common place.
3 Do not talk to him or have any communication with him. (one option)
4 Slow break off is another idea also withthout giving him too much information. (second option)