I don't know if telling both of them about your situation would be nesscarily wise. My reasoning is that if you told each one of them your story, they might think "oh, so there is another girl involved, maybe this guy isn't really what I wanted after all". However not telling them would be risky too, if they found out you chatted with both of them deeply, their feeling will be hurt and they will be angry at you for not telling them. It is risky either way, perhaps it is better to be honest with them to avoid an eventual confrontation. I guess I would tell them, and whoever you chose to date with, tell the other you still want to be friends so there are no hurt feelings