You can set standards that will help you stay pure. "Firmly establish personal standards... Decide what you will do and what you will not do to express feelings." (Richard G. Scott)

Pray and ask Heavenly Father about the standards you have set for yourself. Don't let what happened in the past define your future.

https://www.lds.org/youth/video/chastity-what-are-the-limits?lang=eng