Many try to divide it up and say that the ceremonial law can be ignored, but the social / moral law of the OT cannot, but it's just not that easy to divvy up simply. Like trying to take the golden thread out of a multicoloured jumper. You might succeed, but what use is the thread to you without the jumper and what state is the jumper left in?
Or to talk more morbidly as per our title, if the law was crucified with Christ and in Christ, then choosing which bits apply and which don't is like dissecting a corpse and keeping the organs you think are important or that you like the look of… Very Frankensteinian, not very new creation.
Unfortunately, I'm not going to give a clear answer, (cos I don't know it). Suffice to say that we study the OT law with the help of the Spirit to gain wisdom. In the OT, the law was a custodian of God's people (Gal. 3:24), but now it is an adviser. Before it ruled over us, (Gal. 3:23) now it advises God's people on how to rule (Matt. 5:14, 16).
The early church gave guidance to the Gentile churches (Acts 15:20), but rather than being the final word on the subject, I think it is the beginning of a process of growing in wisdom which is to last the whole of the church age and which all God's people are involved in as they work out what it means to bring the fulness of the kingdom of God into all of creation.