Any information welcome? getting to married and visas to us?

My boyfriend and I met on the internet In Jan..We talk on skpye and messenger very day and night with cam and mircophone. there hasn't been a day that we haven't spoken. We met for the frist time in may, we went on a getway to Real de Catorce here in mexico. Now we are planning to see each other again in a less then a month (we fell in love). we have plans for him to come very month at the most two,but the problem is that he lives in DC and the cost to come to mexico are too much .so now we are looking in to getting married so we can be together. I was born in El Salvador but live in mexico my parents work for a canadian company and our family is in process of becoming canadian residents. Is there going to be a problem with that or am i going to have to give that up? I went to the states when i was little, will i have to prove what i was doing there? or does it not matter beacuse of my age? what do i have to tell the visa interviewer? how do i prove that i really do love him?