Confused !! What to do? It's hurting now

Hi there !
I am a guy and had a guy best friend when we studied together. I had a silent crush on this girl (she was my good friend too) and my friend chose to purpose her. It didn't hurt then cuz I thought it wasn't going to happen within her and me for some other issues.
They both got married and I was so happy for them. Then I got married too.
Our relationships were stronger than ever now.
After a couple of years they left country for job etc. and I got in email contact with this girl. I came to know then that her relationship wasn't going well . Won't go into details but mainly cuz of over-drinking hubby and self-obsessive mother in law.
I somehow was hurt and tried to cheer her out of misery. We began chatting really long and during that we came close to each other. And somehow my old feelings began to interfere. I knew it was stupid so I tried hard to cover them. One day one thing lead to another and I told her that I had feelings for her. She was shocked and it changed a lot of things. I told her I have moved on and do not want to let those feelings ruin our friendship. But somehow things kept changing and foolishly we began to flirt subtly, which encouraged my feelings more and when I was stupid enough to let my thoughts wander she put a full stop to our relationship. I had sleepless nights and it was very difficult to get over her but that was the best thing to do. I was happy it ended and we didnt talk to each other for 3-4 months. Then gradually she began talking again.
Now we talk almost daily cuz she is having another problem which she discusses with me but she behaves so irrationaly. She's trying to get artificially pregnant so it could be hormones or just tension. One moment we're talking just fine and next moment she just offends me so bad (of course then she'd say she didn't mean to offend me) but I think she releases all her job/home etc. pressure on me). I do want to talk to her as a friend but then she would get mad at a silliest of jokes or just gets mad for no apparent reason. I am trying to cope up but it makes me real sad since I don't think its my fault most of the time. I want to get out of it now but she is my best friends wife (also my wife's good friend) and we have to face each other many a times.
Another problem is that since I was attached to her, seeing her in trouble makes me feel like doing something for her or just standing besides her.
Should I just flip out or continue burning my heart until she is free of problems or whatever?

Are you still with your 1st wife? Because if you still are she really dosent deserve all of this.