Walikum Asalam dear Sister;
I agree with Patricia that as the matter was so much private, so you should not have disscused that with his parents.... though its true that in Pakistani culture, we usually involve the family elders, but only at the stage where things are totally out of control.
But do not worry, give your husband time and space. If, what ever you know about his past is ture,.... i guess you should give him some space and time to realize himself that such things are not good....
1. Do not ask him so much questions about where he has been? with whom he was?..... jus show him with a smile and good attitude that you where waiting for him to spend good time with him.
2. Instead of texting him, "where are you?".... text him "i have baked a yummy cake, lets have tea together".... what i mean is that whenever your husband think of returning home, he should not get annoyed by thinking of appearing in your court..... but he must feel relaxed and excited.....
3. make him believe that you do not have any issue with his past.... you are just concerned about his present and future....
4. recite Allah Pak's name YA WADUD'O exact 1001 times (thousand and one) and blow it on some food or water and you and your husband should have it. Insha Allah he will be effectionate toward you.
May Allah Pak bring happiness in your life. Ameen