You have two options:

1) you invite them, and put this all behind you. this is kind of a pushover option, but truthfully, probably the only way you might save your friendship. So it has it's pros and cons.

2) You stand up to them, and say something as nice as possible, while still not inviting them. Personally, I would say something like this "Andy/Steve, the majority of this wedding is being covered by my parents. It is incredibly large because it is traditional to invite friends and family of my parents, siblings, and cousins, including people who we may not be close to, but have also invited us to attend their weddings in the past. Of course I consider all of you to be very close friends of ours, but as you were unable to invite us to your wedding, unfortunately in my culture we have to prioritize those who did. I sincerely hope that you can understand this is not personal. I was also hurt when me and my fiance weren't invited to your wedding, so trust me, I know this hurts you as well and isn't ideal, but I have to honour my parents and my cultural traditions. I would absolutely love to spend a night out with you before or after the wedding and celebrate with all of you, what about XYZ restaurant on XYZ date?".

If you end it with an exact plan to celebrate, they might be able to gloss over this. But really, there is no easy way to deal with this, since they seem to be huge hypocrites. It is also a bit tit-for-tat behaviour, if you are truthfully not inviting them because of them uninviting you. If in your opinion you are truly not inviting them because of this, then you need to assess whether or not you are willing to end friendships over this (maybe you do, if this is only one event amongst others that they have slighted you). So definitely weigh your options.

Look forward to hearing an update to this, I am curious how this is all going to turn out, so please keep us posted!