Is this going to be a non sexual visit? I don't know what would work for you, but for me I would want to focus on getting to know the other party - hanging out, having dinner, watching movies, playing board/video games, whatever you might share in common. From what I've seen lots of people handle PDA's and balancing the needs of the live in partner horribly during initial visits like this, taking sex off the table might help, at least for the first few days of the visit (and that includes taking sex off the table for you and her if you/he thinks its fair.)
Again, no idea where your head is at or if this would make you more comfortable, but unless you can happily forgive her for cheating before he gets there, taking it slow so you can process the feelings as they come up is going to be extra important.
Happiness will never come to those who fail to appreciate what they already have.