Congratulations,
Never be afraid to express how it is that you truly feel. Help him to understand that you have set boundaries for yourself and those around you. That it may take some time for you to become open about your honest emotions.
If he truly cares and honors you as a person, above all else, then he shall respect your wishes. Inform him that you mean not to be distant. Only that you are conservative of yourself, both physically and emotionally.
I'm certain if he recognizes your needs that he will be patient with you and understand. Until an established sense of trust is forged between one another.