My father passed away in Malaysia while I was abroad, and I did not make it home in time. How do I heal this guilt?

Not being able to be there is not a sign that you were a neglectful child; it is Allah's decree, beyond your control. That guilt comes from your love, but do not let it punish you. Your devotion to your father has not ended: pray for him every day, give charity in his name, settle his debts if there are any, and keep good ties with his friends and relatives. Contact your mother and siblings often, because they are grieving too. When you go home, visit his grave calmly. Allah says: “Remember that in the remembrance of Allah do hearts find rest” (Surah ar-Ra'd 13:28). If the grief is so heavy that it disturbs your work and sleep, talk to a counsellor. See mental health.