Nothing has been sorted and he expects just to move on?
@whatasituationisthis you have had a wake up call and a warning that you need to sort your life out with clear boundaries and a fresh look at the partner yiu have chosen to have a child with. You have been coasting along which is maybe OK if you are on your own with him but you both have responsibility for a very vulnerable child. It is both of your duties to do your absolute best to protect your child but you both are failing. This may sound harsh but look at the current situation:
You have a partner who has no boundaries when it comes to contact with another woman.
Instead of reassuring you he refuses to show you the phone and the hundreds of messages sent over a few short weeks by another woman. How her boyfriend is managing or if he even knows the volume is not your or your partners concern. However, if you get an opportunity just tell them while you were not comfortable with hundreds of message exchanges over a few short weeks they clearly are.
You gave up your job to look after a vulnerable child and your partner refuses you access to money. That is something you need to change ASAP. Major cause of concern.
Instead of talking and reassuring you his suggestion is if you can't accept his version is you split up! What protection do you have if this happens? Very concerning attitude.
How often are these trips away with his friends? Is he living the single life while you take care of the home and child? Why is it acceptable for one woman to tag along?
He is now communicating with you by sending messages? Why can you both not sit down and talk?
As I said earlier you have had a wake up call. You need to urgently look at what your options are going forward. You need to urgently address finances, his reluctance to allow you access to money is extremely controlling. You must reevaluate your current situation without separate income. If that means returning to employmen, part time or whatever, you must take action.
Your child must be protected. What are the options for the child if you do split up? Homeless? Mum with no access to funds or income? Having to enter a system (school) that is not suitable for or cannot accommodate their needs? Whole world is turned upside down.
Start planning, get some support and counselling. Communicate open and honestly with your partner not resort to text.