This question comes upon here at least two or three times a month, and the answer is of course it's too old. Whilst you might feel really young and fit at the moment and ready for anything, do not underestimate what menopause will do to you, and how fucked and tired and weary you will feel. And that will only be about 6 to 8 years away ...
Do you really want to be bothering with primary school age children when you're going through the menopause/when you're in your 50s, and possibly dealing with elderly parents as well?! And do you really want a child still at college when you're 60?
There's also a fairly high risk of there being something wrong with the baby. Do you really want to be dealing with a baby/small child with additional needs in your mid 40s (with 2 other children to raise too?) It's hard enough with children that are not SN. You could also have a difficult pregnancy and a bad childbirth. It's also extremely unfair to the child ...
But you will get a bunch of posters on here saying it's the best thing ever to have a child in your mid 40s. It's really not. It's not great for the mother. (or the father really.) And it's not fair on any other children you have. And it is certainly not great for the child... (Being in their teens and having a parent who is nearly 60.) They could end up having to be their parents carer in their 20s or 30s when they should be enjoying their youth and freedom and eventually their own family and children... Don't do it. Just don't do it.
And you are not a 'young 42.' You are 42. Middle aged. That is a fact I'm afraid. I am nearly 60. I feel 27 in my head, but I am still nearly 60!
If your man is 'sobbing' because he really wants children, why did he get into a relationship with a middle aged woman/a woman 12 years older than him FGS? As some posters are saying, it sounds like you are considering this for him. Don't do it. If you split, (say 2-3 years after having said baby,) he will not take the baby you created with him. You will be a single mum, nearly 50, and with 3 young children to look after. You'll get no freedom til you're in your mid to late 60s! Oh and also, you have been with him just 2 years! That's hardly any time at all these days!
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