The downside includes it will go on your record as a criminal conviction. If it is not yet requiring registration as a sex offense, the Legislature is known to expand the list of convictions that does, and at some later date you may be required to register as a sex offender. If you are guilty, the court can require you to undergo a sexual deviancy evaluation and have it returned to the court, where it becomes a public document. With court records now frequently going on line, that means it can be available to the public as long as databases exist on line. This is a crime that is being taken more seriously all the time. You don't want to accept a conviction unless you have no options.
I strongly urge you work with a lawyer and see what options you have. If you cannot afford to retain counsel, talk with a public defender.
In addition to leaving you with a criminal record, there is always the possibility that the law will change in the future to make you have to register as a sex offender, or to add additional consequences as a result of your conviction. Without knowing more about your situation, one could not make specific recommendations, but it is extremely unlkely that a lawyer would simply recommend that you plead guilty.
In addition to what has already been said about the possibility of future sex offender registration I would say that the biggest downsides to a guilty plea would be the criminal conviction on your record, future employers seeing this on your record, and the possibility of a psycho-sexual evaluation. The psycho-sexual eval is a big one. It not only costs around $3,000 but it is incredibly invasive and humiliating. I've spoken to people who have had to go through this and it is certainly a low point in a person's life.
Don't go in a plead guilty. Get a lawyer. Apply for a public defender. The law on this is very specific and there are mental state elements that can be difficult for the state to prove. It is worth your time and money to do this right. You said you want to get past this. Pleading guilty can make it very difficult to get this over. It can follow you around in ways that you will not like.