My GF, another guy, and I were all grad students in the same program. She and I had been together for five years, and we'd been living together for four. She'd known him for one academic year. She had a fling with him over Christmas, spent the spring term oscillating between us, then decided to move out of our apartment when the term was over. To "find herself." To jump his bones, clearly, but it wasn't phrased like that.
The day she actually moved out, I ran a half-marathon up in Westchester so I wouldn't have to be there when all the hustle and bustle was going on.
When I came home to that suddenly-empty apartment, it was very quiet. Almost haunted.
I don't know if that was the saddest/toughest day of my life. I was only 26; just a kid. Half the age I am now.
But that was the last race I ran for 19 years. It would be fair to say that I lost my heart for racing for a good long time.
Love ends. Relationships end. Eventually, even with the best relationships, somebody dies. If you're lucky, you both get very old, you love each other the whole time, and then somebody finally dies.
The pain comes, often, from the fact that we're short sighted: we unconsciously freeze everything at right NOW and then say, "Woe is me! This is horrible and it will always be bad like this!"
But that's not true, unless we choose to make it true. Things keep changing. If you allow them, they keep changing in ways that may include great happiness somewhere beyond the present horizon of great unhappiness.
That's what happened to me: a second 5 year relationship--it ended because we simply couldn't stand each other's guts--and then, somewhat later, the wonderful woman I'd been waiting for all those years. Now I've got a 5-year old son who tells me to shut up, daddy, you big pootie-head.
I guess that's happiness.
To the OP: don't let your wife's apparent position of superiority--she's got a guy and a sparkling new house; you're having money troubles--fool you. Things keep changing. Give them a chance to.
My GF from long ago? She lasted almost two decades with the guy she left me for. They had a kid. Great kid! Then he pulled all kinds of crap and eventually she left him. She's happily married now to HER dreamboat. And we're friends.
Things keep changing. Take the long view.