Are these usages of pronominal verbs correct to translate “She opened up to me”?

Question

Are the following examples proper ways to say, "She opened up to me":

Ella se abrió a mí.

A mí ella me abrió

Ella se me abrió.

A mí ella se me abrió.

I'm using examples of the idiomatic pronominal verb abrirse.

Answer 1

In the examples with se, the meaning of the verb would be (as intended) something like "to open up", in the figurative sense (letting other person know about one's feelings or intentions). This is meaning #30 of the entry for abrir in the Diccionario de la Lengua Española:

30. prnl. Dicho de una persona: Declararse, descubrirse, confiarse a otra. Se abrió conmigo.

Note how the definition employs the verb confiarse (a alguien); that's another pronominal verb.

Using the preposition a for the recipient of the action is not usual in this meaning of abrir (as you see, the example in the DLE employs con), but it's OK.

Your examples with se are pronominal. Se acts like a direct object and refers back to the subject, which is third person ella. If the subject were first or second person, singular or plural, the pronoun would have to change (it would be me, te, nos, or os).

The recipient of the action (me) appears as the indirect object, in two ways: as the clitic (unstressed) pronoun me, and as the full (stressed) pronoun mí preceded by the preposition a.

The three pronominal examples mean the same: "She opened up to me." Only the emphasis is different. There are some complicated rules governing how to use the two types of pronouns and the word order, which I won't cover here.

The sentence without se has abrir in its basic sense. As it is, it would be usually understood with an implicit direct object (the thing being opened, a door?), and the indirect object would be the beneficiary of the action. In your example the unusual word order shows topicalization:

A mí ella me abrió. = "For me she opened (the door)."

If you don't need emphasis you would just say:

Ella me abrió. = "She opened (the door) for me."

Note that in English you open the door for someone (a benefactive construction), while in Spanish you "open someone the door" (abrir works as a ditransitive verb).

Alternatively, the verb might work as a transitive form of its (usually intransitive) pronominal version:

Ella me abrió. = "She opened me up." or "She got me to open up."