"Forgeting" should be "Forgetting".

"You need to forget about your past
your heart might be in the future but your head is in the past."

These two lines were good and you got your message to whoever you are speaking to across with strong words.

"you need to forget wat happened then and realize u could lose the person that loves u more than anything if u don't let go and start new cuz he loves you."

This was a bit of a run-on and you have many spelling errors. Try this:

"you need to forget what happened and realize you could lose the person that loves you. He loves you more than anything, and if you don't let go, and start new, you will never forgive yourself. Remember and keep in your heart this: he loves you."

Hope this has helped! Just remember you don't have to rush everything together, a bit more detail is fine.

God bless you and Merry Christmas!

~MaryAnne