Need advice ASAP

No judging please!
My boyfriend and I have been together for two years of school. Before we met though he did not tell me that he was on the Internet searching for "love", he thought he found the one, they started hanging out and everything that lead to sex sooner or later the girl then responded that she was only 14 years old. My man was locked up because of that but at the time I didn't know him. He then got arrested and went to prison because he failed to register. He is only in prison for another 10 months. I love him and all the times that we spent together because I know mistakes happen and the girl didn't tell him her real age, she said that she was 18. What should I do? Should I stay with him? He is a really really nice guy sweet and caring, but his past scares me even though he hasn't been involved with anyone else because he's dating me. I Kinda really sucks because the girl lied about her age, and then he ended up going to jail. I need advice on what to do