[Vocabulary] What is the meaning of "it speaks to state of mind" in this context?

[Farshad.021]

Hey guys, hope you all are doing great. My question is about the newly released TV series called "izombie".
first, I'll give you the context.

As you might know, this show is about a girl, a medical student, who goes to a party and suddenly turns to a zombie who has a desire for eating human brains.

Now, she is a zombie and everything in her life has changed. She broke off her engagement, she is not as passionate as before, most of the times she just sits and watches TV. So, her friend and her family think that she has PTSD and want to help her. One day when she comes home, she sees her family, friend and fiance.
Her Mother says: you will regret breaking off your engagement to Major till the end of time. Do you have any idea how many women would kill to be with a man like this?
Her fiance says: I was told that, um, we wouldn't be bringing up the engagement today.
Her friend says: It's evidence. It speaks to state of mind.
her fiance: I was also told we're not putting you on trial.
Her friend: Hey, you're not on trial.

I don't understand the meaning of underlined parts properly.

Does "regret to major" mean "regret a lot"?
Does "It speaks to state of mind" mean "It's something that helps her recover or something"?
Does "put someone on trial" mean to "bring someone to the court"?

Thanks in advance,

 

[SoothingDave]

1. "Major" seems to be the name (or nickname, anyway) of the fiance. The word is capitalized.
2. The evidence testifies to her state of mind.
3. She is being put on trial metaphorically. Her friends and family are questioning her actions and accusing her of some sort of poor behavior.