I'm 43 and I now know what love is supposed to be about and feel like!
No, from everything you've written, it looks you don't.
Love is not a feeling you get after knowing someone for a month. Love is not sleeping around and blaming it on alcohol. Love is not blaming the alcohol use on the person you're sleeping around with. (That was an interesting switcheroo though.) Love is not ruining someone's Thanksgiving with dramatic suicide threats.
Love is an action, not a feeling. If this scenario is what you think love is, then you may want to consider therapy. Your ex-wife seems to be showing a lot more of what love is than your girlfriend is showing.
You know, ask us how many of us here stubbornly "knew" that our A was a good person and the love of our life? I'm raising my hand. I "fell in love" with my X after about a month and we got married 5 months later. I thought I'd finally found out what love is. We were happy for a couple of years, then the heavy drinking crept back in, and eventually, he had an affair and left.
It took all this for me to learn about what love really is and isn't. I've learned that people who fall in love too quickly have problems. I had problems and my X had problems.
I hope that you don't have to put your daughter through what my daughters have been through.