Hello Radcliff and thank you for your thoughtful answer, as I've opened a new post two days ago (which you had also replied to), I will answer you there, because the information there are more up to date.
https://bpdfamily.com/message_board/index.php?topic=330409.0As you can read here, I have already told him by now. I told him because I didn't wanna hurt his trust further and I remember how much it hurt me when he never said anything but "Ohh I have new girlfriend since yesterday"... .I think shock news are more hurtful than preparing someone... .And I really hope he will stop me from letting this become serious... .