All of this is meaningless if you can't answer my points: I'll reiterate and clarify.
(1) Where is the historical record of persecution of Jews by Christians after the book of Acts? (I'll grant you James the Just, but that hardly deserves the destruction of Jerusalem.)
God knows. Why do you need a further historical record? The Jewish leaders didn't suddenly repent & turn to God after their assault on Paul.
In any case, AD 70 was prophesied by Jesus in his Olivet prophecy. Moses prophesied judgment on those who refused to hear their Messiah. (Deut. 18:18-19, quoted by Peter in Acts 3)
(2) If there is no such record, why would God destroy Jerusalem for the persecution recorded in the NT? (No one but Stephen was killed for Christ in the NT.) I think your point is insufficient here, since you give nothing but your opinion that their stubbornness, etc., was the reason. Give Scripture for that point, not just Stephen's statement, which promises no judgment.
You assert - (No one but Stephen was killed for Christ in the NT.)
Acts 12:1 Now about that time Herod the king stretched forth his hands to vex certain of the church. 2 And he killed James the brother of John with the sword. 3 And because he saw it pleased the Jews, he proceeded further to take Peter also.
The judgment was not just for that persecution, but for their rejection of Messiah, & the Apostles, & prophets down the centuries:
Mat. 23:34 Wherefore, behold, I send unto you prophets, and wise men, and scribes: and some of them ye shall kill and crucify; and some of them shall ye scourge in your synagogues, and persecute them from city to city: 35 that upon you may come all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias son of Barachias, whom ye slew between the temple and the altar. 36 Verily I say unto you, All these things shall come upon this generation.
I suggest we can be confident that Jesus' prophecy of persecution would be fulfilled by the Jewish leaders.(3) The persecution of Christians by Nero was far greater than any by the Jews, even that mentioned in the NT. Why did God not destroy Rome then or judge the Romans in some other way?
The Israelites & Jews had covenant promises from God; Nero had no such promises. And he did not go unpunished.
Hebrews is helpful -
10:26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, 27 but a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries. 28 He that despised Moses’ law died without mercy under two or three witnesses: 29 of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace? 30 For we know him that hath said, Vengeance belongeth unto me, I will recompense, saith the Lord. And again, The Lord shall judge his people. 31 It is a fearful thing to fall into the hands of the living God.
Jesus have lived with them for 33 years, & taught them for 3. They had received knowedge of the truth direct from their Messiah. then from the Apostles.