hello everyone

So I did confession, and I ask my Priest the same question I asked in this thread:
http://www.orthodoxchristianity.net/forum/index.php/topic,48036.0.htmlThis might be a complicated question, so bare with me.
He told me that a sin of hating someone (not just being frustrated with someone, but actually hating them) or a sin of sexual immorality will exclude me (or anyone) from communion. He then told me to pray the "Jesus Prayer" throughout the day. I then asked him "if I do fall into a bad sin (like sexual immorality), can the Jesus prayer cause me to be forgiven and able to partake in communion." He told me "no", I would have to confess that sin before communion.
So my question is, what is the point of the Jesus Prayer? This may seem like a mean question, but if the Jesus Prayer wont prepair me for communion or cause my sin to be forgiven, then why would I pray it? This goes for anything in life. If punching my PC wont fix it, then why would I punch it? if yelling at a new born baby to stop crying wont cause the baby to stop, then why would I yell at it?
Can the Jesus Prayer only cause "minor" sins to be forgiven?
Thank you in advance