i dont know what to do anymore
A tricky situation with multiple angles - makes it difficult to comment with little information available.
First of all I'm sorry to hear that you're distressed. I know what it feels like to be dealing with these issues and having to work at the same time.
I think the best course of action, if your wife continues to accuse you of such things is to get some professional marriage counselling to nut out the underlying issues. In the meantime I think it's probably best to tell her, firmly but calmly that you are not cheating and love her - end of discussion. She'll probably be looking at your emails and phone so as long as your happy with that. Actions are better than words in some cases. She may be feeling insecure for other reasons - such as money being tight, new child on the way, issues with current children?? So I would make sure I'm contributing reasonably to care of the kids and maintenance of the house. How come you're not licensed? Can you get this back so you can start earning more money. This is obviously an issue for yourself too, so getting it sorted would be a win win. I can see the appeal of the army, however I can also see your wife's angst at you being away for periods with her having three kids to look after.
As I said it's complicated - your wife has trust issues for some kind of reason, whether it be real, imagined, ? hormone induced? I mean if you're going out heaps and coming home late all the time I can understand her concerns but if that's not the case (and apart from random woman in ? your contacts list) I'd want to know why else she keeps suspecting infidelity. Number 1 makes sure you're present and active in family life/around the house, and if in doubt get professional advice - maybe individually first and if necessary with your wife too.