All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.What you have mentioned in the question indicates that you suffer from Waswaas (obsessive satanic whisperings). If this is the case, you are advised to disregard those whisperings and any similar thoughts that come to your mind in order to avoid incurring more serious consequences and cause damage to your life and religiosity.To sum up the answer to your question, there is no blame on you for using this fridge or any other item of property that was purchased with this money. If there arises evidence that the father was not entitled to it, then the forbidden nature of the act falls under the father's responsibility.We highlight here a valuable quote from Ibn Taymiyyah  related to this, which can serve as a great principle governing interactions among people. He said,"The presumption concerning whatever is in the possession of a Muslim and what he claims to be his property, is that it is his rightful property. If I do not know the status of the property in his possession, I base judgment on the presumption. Further, if in the same instance he did unlawfully take possession of that Dirham (for example), and I did not know, then I would then have been unknowing, and what is unknown is (effectively) non-existent." [Majmoo' Al-Fataawa]Allaah Knows best. (Source: islam_web) Classified in Fiqh of Transactions and Inheritance > Other Types of Transactions