I am so sorry that you find yourself in this painful situation. It is sad when one does not feel loved by a parent and when one cannot offer that love. The abusive treatment you experienced clearly left deep wounds that remain tender. While your question lists several behaviors by your father that you object to, it is only the question of abuse that is relevant to the question of whether you must mourn his eventual passing or not.
There are two key issues embedded in your question. (1) What are the limits of the command to honor one's father and mother, at least regarding mourning. (2) For whom are the rites of mourning intended?
(1) It is worth noting that the Biblical command is “to honor your father and your mother” (Exodus 19:12). To honor, not to love. The Torah, and the rabbis in turn, are aware that abuse exists, that not every filial relationship evokes feelings of love. As a minimum standard the tradition mandates that the child assure that the parent has food and drink, clothing and shelter. The cost of these expenses is to be borne by the parent. Additionally the task of seeing to these needs can be assigned to an agent. (Maimonides, Hilchot Mamrim 6:3)
While this minimal reading of the obligation allows a child to create distance between themselves and the parent, distance that may be necessary for the child's protection, it falls short of answering if there are circumstances in which the obligation does not hold.
Rabbi Mark Draitch, the founder of Jsafe (The Jewish Institute Supporting an Abuse-Free Environment), discusses this as part of a longer article, Honoring Abusive Parents, which appeared in
Hakirah, the Flatbush Journal of Jewish Law and Thought. In considering those who might be considered exempt from observing shiva he note the following:
Rema adds to this list those who sin on a continuous and regular basis, even if they do so le-teyavon ̧out of a lack of self-control. R. Eliezer Waldenberg notes that Rema would also disqualify from this list those who violate a commandment le-hakhis (intentionally), even if that violation is not on a regular and continuous basis.
Draitch proceeds to outline a debate in the classical sources on this question, but then states clearly:
Nevertheless, an abused child is not obligated to mourn an abusive parent and may not be compelled to observe shivah, sheloshim, or the twelve-month periods of mourning.
I take seriously your statement that when you and your father have spoken “it just opens old wounds and literally makes me ill - physically and mentally.” As if in response to your comment Draitch specifically states that
it may be cruel for us to impose mourning rituals on these children. After all, being compelled to perform acts that honor an abuser may be abhorrent to the victims and may create additional feelings of resentment against the perpetrator, the community, and the tradition that places this onus upon them. In addition, listening to tributes for parents that children know are undeserving and unworthy further victimizes those children emotionally.
He goes into much more detail than I can include here. This is sufficient to allow me to say that the tradition certainly exempts a child who has suffered abuse at the hand of their parent from observing mourning.
(2) That leads, however, to the second question: for whom is the mourning intended. If it is for the benefit of the deceased, then Rabbi Draitch has provided a sufficient answer. If, on the other hand, it serves a productive, healing purpose for the survivor, then perhaps a case can be made that you would benefit from observing rituals of mourning.
It is conceivable that observing the rituals of mourning may offer a path to healing, either by using traditional observances or opting for more contemporary options.
Rabbi Dr Joel Wolowelsky theorizes that “opting out of the mourning process would only cement the lifelong feeling of betrayal... [Mourning an abusive parent] might just inspire individuals to seek help in coming to peace with their past” (cited in More Than a Tear: A Shiva Guide for Mourners and Consolers, by Yigal Segal). While clearly recognizing that “the halacha exempts abused children from sitting Shiva if they would suffer emotional distress,” Segal suggests that the process may offer a way to look forward to a future wholeness.
A similar outlook, though using less traditional practices, is offered in the book, Sexual Abuse in Nine North American Cultures: Treatment and Prevention, edited by Lisa Aronson Fontes (pg. 154ff). She suggests that some form of mourning may release some of the grief and sense of betrayal surrounding the abuse.
She cites this example that was published in the Valley Women's Voice by M. Wolf:
Sitting shiva for one's abusive parents is indeed a holy and spiritual process... The mourner is taken care of by her community for a period of time...one cries and tells one's story and feelings so often and with so many supportive mirrorings being reflected back, that it transforms one's memories from painful stones in one's shoes to threads lining the back of one's coat. In other words, what one has suffered no longer is a source of new original fresh pain, but part of what is behind you and magically transformed into something that protects and keeps you warm.
Aronson Fontes also notes the examples of those who have used the mikveh, the ritual bath, to provide a sense of spiritual cleansing and purification. Also, she offers the suggestion of creating affirmations that can be used through the time of mourning or in daily prayer/meditation. All of these have a goal of helping one connect with their cultural, historical, and spiritual background.
Clearly, based on the opinions outlined by Rabbi Draitch, you may choose not to observe mourning rituals for your abusive father. Alternatively, it may be worth considering if there are ways in which some traditional or contemporary rituals may serve you in your process of healing.
Finally, I would note that there is another question on the Jewish Values Online site that may offer useful insights: http://www.jewishvaluesonline.org/question.php?id=546&cprg=%2Fsearch.php%3Fsearchtxt%3Dabuse%26what%3DA