"Are they going to get married?" Slow down a little there, lol. Whatever it is, good or bad, it's not going to help you to obsess and work yourself up over. You're strong enough and capable of handling whatever it will be fine.

I think the 2 years seems to be completely reasonable and I've thought about it myself. It doesn't put your own feelings into the mix since it's what's best for kid and X should be able to see that. At some point in the future (2 years down the road) you will have to accept they may interact but cross that bridge when you come to it. Their relationship may not even last that long so no reason to obsess over it.

Accept what is, let go of what was, and have faith in what will be