In Texas, if you kill someone while committing a crime, it is murder, plain and simple. Easy decision.
She entered illegally (breaking and entering with no warrant). The law has no provision for “I made a mistake” .
Now the hard part -—sentencing -— which is where all the other factors can be considered.
She pushed on the door and it swung open, so there is no "breaking". Doors swinging open is what one expects when one is trying to enter one's apartment.
Calling it a "crime" is making light of what constitutes a crime.