Tough. I think you should tell the facts to your father. Tell him current status, your keenness to marry him and ask his advise about what to do. This will definitely act as a breather. You will be able to deal with guilt to some extent and get emotional support. Transparency about current status of your relation will keep your familial support intact. You also let him know that you do not want to hurt them and at the same time not able to leave him. Ask your lover to negotiate with his parents continuously rather then maintaining status co. Ultimately, you may have to be prepared for displeasing some one, your parents, his parents, him or yourself.