Advice please - desperately needed

Hi all,

So on Monday, after nearly 15 years together my partner decided to end things. We have had a lot of struggles in the past 3 years, mainly down to my struggles with money but we decided to work through it. 1 week ago, we were actively trying for a baby & he was pursuing me saying we needed to do it because it was the right time.

Fast forward to Monday & he doesn't want to be with me anymore, because he's been messaging a 21 year old he's worked with for 6 months for this past week.

Ive seen the messages he's sent her & he's claimed to have been unhappy and told her, she has made him smile for the first time in ages - I can tell you now he was smiling alright a week ago when we were going at it.

I understand it's still so raw, but he's been so cold & callous & he's so chilled, after ripping out my heart and smearing it across the floor. He doesn't feel or can even begin to comprehend the pain I'm feeling, because he's lied to this girl, laid it on super thick all while having sex & trying for a family with me.

We tried at what was the right time according to opk's, so only time will tell if we've been successful - if we have been I will be keeping the baby, but though my heart is in pieces I have no desire for him to be in my life.

The advice I'm so desperately craving is if I should send a message to this girl, calling out all his bullshit. I'm 31 & hes 32, but we have been together since we were 16/17, he has never been so cold as he has been this past week and that's purely because he can justify his behaviour by being so disgustingly brutal.

I have a message penned and it has helped me writing it, but I'm not doing it because I want him im doing it because I want her to know what a vile person he is and what he is capable of.

Should I do just that and send her a message? I want to be very careful to not come across as the crazy ex misses, or shall I swallow all this and try to process what he's done?

I want him to feel an ounce of what I feel and I want her to know, that he's a bullshitting little boy with very little respect for anyone?

Help really appreciated@!!