Tony,
It looks like a classic weld failure due to lack of weld penitration that was exascerbated by corrosion. If you look closely you may see some transverse scalloping of the weld failure interface. Like tree rings, this would tell you that the failure happened over multiple actuations rather than in a single event. Careful inspection may have caught this before complete failure.

The good news is that the fix is easy as the strut arm is not part of the actuator chamber so you can re-weld the tab without disassembly of the strut. You will need to remove the strut so you can properly prepare the area. It would also be a good idea to make a locating fixture for the tab so that it can be repositioned properly.

The great news is that you made it back to terra firma without damage.

Brent Regan