I had friends I considered family...who did prove themselves through thick and thin, supporting me through some pretty difficult emotional times. I would NEVER have conceived of their not being in my life. I did help to support them financially (rightly or wrongly, I don't like seeing children going hungry and hey, we were all brothers and sisters in the congregation - you received free, give free, right?). I never loan money and expect to see it back. It's great if it happens, but not counted on.
In the end, a business deal we were attempting fell through and they left me holding the financial bag. They didn't "mean" to, but then again they didn't "let their yes mean yes", nor were they honest in their business dealings with me to start with. For my part, I trusted them to deal with me as I was dealing with them. It didn't happen. When I forgave them for that action, they then stabbed me in the back and lied about me. They stole money and property from me.
Since leaving JWs, I have chosen my "family", who include 3 lesbians in a polyamorous relationship, a variety of malcontents in varying degrees of emotional and financial stability, and my sweetie fiancé. I trust these people with my life, and love them to death, but wouldn't necessarily enter financial arrangements with them (well except the fiancé of course...).
The lesson I learned was that friends can be fantastic but that no matter how long I've been friends with someone (they were 10 years!) I can never *really* know how things will turn out in various situations. Money is a big trigger situation.
As for your ex, well mine stalked me for years so my feelings may not be as supportive (or unbiased) in the "should you see him" category.
edit: Damn, y'all are moving quick on the thread! As long as you're both covering yourselves legally to the nth degree, and you both are aware going in, I think it's a good thing for you. Extracting yourself would probably be easier than a divorce and I understand completely not wanting to be alone. Best of luck to you!