Like everyone else has said... yes... be a friend. Be a friend. Be a friend.
To help HER, firstly. Then yourself. Then your wife.
If you become involved with a fragile person (regardless of divorce), it can be extremely, extremely hard work. It can be heartache at worst and a complete and utter exhaustion at best.
It's such a cliche, but the old thing about spending time on ourselves is so true.
Think of relationships like a hot water bottle. Let's say she is the water bottle and you are the water. The bottle has a hole in it right now - so where's your water going to go? Yep, all over the floor and make a right mess (that your wife will probably have to clean up). When her damage is repaired, then you can come in and have something more comfortable, more healthy, more cosy and long-lasting. As the water, you can't come in too hot (romance now), nor too cold (withdrawing all contact). A nice balance is needed.
As for HOW you can maintain a friendship without the extra stuff?
Some people say this is impossible. I disagree. I can't control the feelings of my partners, but I can (and do) control the way I act about my feelings towards them.
If I am trying not to become emotionally involved with somebody, I basically avoid phrases that can get their heads all wrapped up in our friendship or relationship. My last secondary, for example, seemed to be starting to get very, very emotionally attached. She'd come out of a relationship 6 months earlier and it was clear to me that she was transferring her feelings for this woman onto me during the first month or so of us dating. She would start texting me when she woke up, telling me she opened her eyes and thought of me. I could see exactly where it was heading. Without being cruel, I basically reigned it in and made sure that I was being responsible with her emotions, as she seemed to be more vulnerable that I first thought. This helped and she started to stable out and not seem so giddy about our relationship.
"You're on my mind."
"I am absolutely here if you need me."
"I can't stop thinking about you"
"I was just wondering how you were doing?"
"Our connection is so unique/mind-blowing/special"
"I really care about you as a person"
Reigning-in behaviour examples:
- Don't be texting intimately - i.e. "I think of you when I wake up and when I fall to sleep"
- Don't be spending hours and hours and hours every night talking
- Avoid getting into a daily-contact routine, as you easily become their crutch, which distracts them from their own faults or pain
Do you kind of see where I'm coming from? I'm not saying be mean - I'm saying, keep it friendly, supportive, without enticing sexual or loving feelings from her.
Just because you are poly, doesn't mean that you are 100% open and available 100% of the time. Not only would you want to be slow here if you were single; but you'd want to be especially slow because you have your wife (and their friendship) to consider.