Relationship Advice

As the title says, my first love whom I've missed dearly has just contacted me and it's thrown my world upside down. We met when we were both 14 and spent a little under 4 years together. It was a wildly inappropriate relationship from the start by the standards today, but we both suffered abusive and absent parents, so found each other. We spent all the time we could together, at the cost of our studies, friends, what little family there was and all else. We were absolutely codependent, physically living as adults and were each other's worlds.

I'm now marred to my wife of 20 years and we have a home together, no children but a successful life by any measure. I love my wife dearly and tell her almost everything, she knows about the contact and encouraged me to start a conversation with my first love. I've avoided difficult things in the past, employing avoidance rather than facing things head on, and this is why she encouraged me.

It's been wonderful to speak to my first love again, and it's brought up emotions I thought long gone. I'm not sleeping, eating little and completely preoccupied by thoughts of what we once had; I feel love sick, but for a squandered past, not a realistic present. I'm bipolar so this is particularly dangerous for me and for anyone else out there like me, I'm working to try and stay grounded, away from the mania and get some rest, but it's hard.

I broke off the relationship back then, because I was afraid of what we were committing to and because I was being manipulated by a very toxic group of people who in hindsight, only wanted to sow chaos and take pleasure in my humiliation. I was not diagnosed back then and so was particularly vulnerable when experience the extremes. If I knew now what I knew then, I would not have been so reckless with her emotions, as it caused her immense pain and led her on a path of self destruction for a number of years.

She's has moved back to near where I live after being on the other side of the country for the past nearly 3 decades. I desperately want to meet her for coffee and look at her eyes again, but I'm also supremely cautious because I don't want to upset my wife and am also afraid of what I might be feeling.

Any advice gratefully received on how I navigate this. I should also mention that whereas I don't have children, my first love does and two of them are quite young, one is an adult.

---EDIT---

Thank you all of you for your advice and guidance, and for your kindness in share it with me. I ate some food last night and have slept, which has brought the mania back down to a more manageable level, and with that I've taken on board and heard all that you've collectively said.

My plan is to talk to my wife this weekend about what I've been going through and ask how she would feel about having a coffee with my first love. I really thought through what matters most to me and it's the present, the future and that is with my wife. She's a wonderful woman who has helped me through so much and my life now wouldn't even be recognisable to 18 year old me. Through her I found the strength to recover from addiction, face my mental health demons, go to University and become the successful privacy lawyer I am today. All of this would not have happened without her strength and support.

If you're reading this you probably wonder why the voice above the edit, and the voice below it, are so different in tone; the answer is my bipolar disorder and it's sometimes extremely hard for me to see that change happening.