The phrase "altered me" is correct and usable in written English.
It can be used to describe a change in one's character, behavior, or perspective due to an experience or influence.
Example: "The journey through different cultures altered me in ways I never expected."
Alternatives: "changed me" or "transformed me."
That summer altered me forever.
Since 1953 New York has implanted itself irrevocably in my being and altered me forever.
"As the words were leaving his lips, I think it physically altered me," Mr. Pritzker said.
"It has profoundly altered me to the very core of my being," a remorseful Avary said in the courtroom.
That is until he witnessed her ability in sparring, an event which he remembers "altered me totally".
It might have been India, and being delirious with the bloody flux, but the work stunned and altered me even though I had no idea what Pirsig was ultimately saying.
I have been good to this person, this alter ME, and look how she thanks me.
"It would always be strangers like them, at the various cat's tables of my life, who would alter me," Ondaatje writes.
But in his book "The Audacity of Hope," he sounded prescient about the dangers of the money chase, noting that he could not assume it "didn't alter me in some ways".
Observing himself with the same care he brings to his patients, Erik remarks on his uncharacteristically obsessive behavior in relation to Miranda: "My solitude had gradually begun to alter me, to turn me into a man I had not expected.... I've often thought that none of us is what we imagine, that each of us normalizes the terrible strangeness of inner life with a variety of convenient fictions".
I get that now, but for most of my adult life I've really thought, this is who I am, I might change or grow in subtle ways but making a change that's so out of character would alter me entirely.
