This one is a full telenovela in four minutes. The singer wants to tell his girlfriend the news himself, "antes de que otra persona a ti llegue" [before someone else gets to you] with lies. The truth: there is another woman in his life, and she is pregnant ("lleva en su vientre una inocente criatura" [she carries an innocent little creature in her womb]). He has decided the baby will be born, "darle vida a esa vida" [to give life to that life], even if it means his girlfriend ends things.
Then the chorus gets almost petty. He pictures his wedding to the other woman, with the priest saying "El novio ya puede a su novia besar" [The groom may now kiss his bride], and tells his ex "me vas a extrañar, me vas a llorar" [you are going to miss me, you are going to cry for me]. Useful tip: el padre here is the priest, not a father, and novio/novia means both boyfriend/girlfriend and groom/bride. He still says it was beautiful to know her and that he felt real love by her side, so it is half apology, half "you'll regret this", which is a bit much, and very entertaining.