Even if it’s all true it’s sure not to change Harry’s mind.
It’s always better to keep your peace and let people figure things out for themselves.
When it comes to weddings, the single greatest benefit or mistake in a person's life, I must disagree. Family members should voice constructive opinions, even if it is to state why they believe the persons should not marry. The couple can weigh those opinions for themselves; but after they are married and especially if they have kids, it is too late. It's just regarded as undermining, then, and it often is by jealous in-laws. But the prospective family has a right to know the nature of what they are marrying into or bringing into their own circle.
If this man's accusations are true, that she destituted her father in pursuit of her career and then dumped him, this is a very serious matter that should be investigated by her prospective groom.