[dentist90]

Late to the party again...
It is unusual to break a virgin tooth like that, usually there is a large amalgam filling that has weakened the tooth. If that piece broke off 'quietly' (without a large crack sound/pain) that fracture has been slowly growing for many years. I have seen a few of these (virgin fractures) over the years and most of them we suspect originated with an upper cut or blow to the jaw that slammed the teeth together and started a small crack. Like your windshield, the crack slowly progresses until fracture occurs.
Your fracture is in the 'iffy' zone. If it had fractured right down the middle thru the pulp it would be a goner for certain. If it had broken above the gumline it would be a cinch to crown it. Yours in kinda in between. It appears to be 4mm or so below the gumline and it was still attached to the periodontium, as you said. The pulp (nerve) may be an issue but root canal treatment can remedy this. Simple vitality testing might reveal how the tooth is doing nerve-wise. A normal healthy tooth should be cold sensitive but not result in lingering pain.
The bigger problem is how to get the crown margin down to where the tooth broke without irritating the gums long term. As Nickshu said, the periodontium likes to have 3mm or so between the bone and the restoration margin. Your tooth is probably broken down near the bone level already, so gum surgery to lower the bone level (crown lengthening) would be ideal. But it is difficult to do this on the palate sometimes... it leads to weird gum contours on the palate. So I think the decision as to whether the tooth is restorable will depend on how far down the fracture went. It is also difficult to make an impression that goes 4mm below the gums.
However... I have crowned teeth like this many times without crown lengthening surgery. I have placed the crown margin 2mm or so below the gumline but not all the way down to the end of the fracture. The margin of the crown is feathered down to a very fine edge that is virtually flush with the tooth. The gums just snug up against the little bit of exposed fractured dentin and all is good. That is what I would want done to my tooth if it is feasible.
Many dentists will advise extraction and place an implant. I place implants too and they are great for missing or hopeless teeth. I much prefer them to bridges in most cases. But the tooth you were born with is the best 'implant' you could hope for. In my opinion the attachment of an implant to bone and the cuff of gum around it is no more robust than what you would have if your tooth can be restored with a crown, even if your tooth has a sliver missing down to the bone level.
If you do lose your tooth at least we have the technology to replace it with a bionic one. Best wishes!