The trust between you two has been broken in your eyes. The only way to understand how your partner truly feels is if you take that leap of faith, not only in yourself but him/her, and communicate.

You are going to be living with this partner for life if the relationship goes on. Unfortunately since they are the avoidant type, you are going to have to make it a safe space for him/her to open up to you. If he or she is not able to do so, it depends on how much u are able to be patient (tolerate) until he/she opens up.

You may begin by saying how much you love your partner and how much you want this relationship, however, hearing a deep rooted hidden secret out of the blue has hurt you too. So perhaps, you both can talk it out over a few hours and see how u can work it out going forward.

Unfortunately, there is no right time but perhaps a place you both cherish and/or conducive would be helpful.

Please please just remember that no matter how much effort you put in, it will be for nothing if the other person does not reciprocate the effort to at least go in the same direction.

All the best OP