Was Constantine innocent?

Perfect example of sources and intent of the makers of videos/programmes - this one’s not too bad:

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0017383500029156

This below though is trashy and was always going to rip denominations apart, not to mention the Abrahamic religions themselves.  He’s honest on two counts, not on the others:

https://youtu.be/KU_NjN7pgdk

1.  His knowledge of early history is good on many points but highly slanted, highly selective, which is to be expected from a Jewish person wearing cap when dealing with Christians. His manner is measured and therefore his subterfuge is concealed.

This is shown in some comments on Helena. 

Christianity didn't become the official religion of the Roman empire until 65 years after the death of Constantine [who] only legalized all religions which included the then persecuted religion of the Christians known as Christianity.  Christianity was declared a tolerated and protected religion in 313AD, the State Religion of the Roman Empire in 379AD and the only permitted religion in 390AD.

2.  Far more concerning is the sun symbol in Catholicism and Orthodoxy, plus other trappings posts passim.

3.  Coming back to the Cambridge contention at the top, it's as well to look first at a few synopses:

https://en.wikipedia.org/wiki/Constantius_Chlorus

Constantius was either married to, or was in concubinage with, Helena, who was probably from Nicomedia in Asia Minor.[47] They had one son: Constantine. In 289 political developments forced him to divorce Helena. He married Theodora, Maximian's daughter. They had six children.

https://en.wikipedia.org/wiki/Helena,_mother_of_Constantine_I

https://en.wikipedia.org/wiki/Flavia_Maximiana_Theodora

https://en.wikipedia.org/wiki/Constantine_the_Great

Maximian, brought out of retirement by his son's rebellion, left for Gaul to confer with Constantine in late 307 AD. He offered to marry his daughter Fausta to Constantine and elevate him to augustan rank. In return, Constantine would reaffirm the old family alliance between Maximian and Constantius and offer support to Maxentius' cause in Italy.

https://en.wikipedia.org/wiki/Fausta

This is the one - Fausta - who seems a bad woman, inconstant, cheating or imagining it, possibly pregnant and needing to abort. She and Crispin are the subject of this post, Crispin being Constantine's son:

https://en.wikipedia.org/wiki/Crispus

Did they, those two?  Is this why Constantine executed both?  Or is there another explanation?  The Cambridge article maintains there was.

It's complicated by this:

In 307, Constantine allied to the Italian augusti, and this alliance was sealed with the marriage of Constantine to Maximian's daughter Fausta. This marriage has caused modern historians to question his relationship to Minervina and Crispus. If Minervina were his legitimate wife, Constantine would have needed to secure a divorce before marrying Fausta, which would have required an official written order signed by Constantine himself, but no such order is mentioned by contemporary sources. This silence in the sources has led many historians to conclude that the relationship between Constantine and Minervina was informal and to assume her to have been an unofficial lover. However, Minervina might have already been dead by 307. A widowed Constantine would need no divorce.

https://en.wikipedia.org/wiki/Minervina