Look up the grief pathway, op.
you are grieving for loss of your partner and your marriage, and facing a massive change with all the uncertainties
what you are feeling, after a shock loss such as this is normal. Be kind on yourself
Your thoughts along lines of “if I’d done this…” are very normal as part of that grief pathway
when you are ready, use the link above to ADVICE NOW. They have brilliant guides to “diy” divorce, informing you about how to get a financial settlement, the law on “fair settlement”, how to go through various processes and form filling. They tell you what you need a solicitor for, what you don’t and can easily do yourself, and where you may want to use one given your own. Circumstances.
remeber that fear is caused by the unknown. Replace the unknown with information, and with what your future life will be like . Do it slowly, get to point where you can actually visualise your future life such as where you’ll live, how child custody will probably work out, what financial situation will be based on this “fair settlement” law. All of those will help to gradually move you forwards with a purpose
do not be afraid to go to GP for help. You may find some sort of counselling helpful, or you may even find, given your mood right now, a short course of antidepressants may help lift you
it’s not easy, especially after being blindsided. But you will manage.