You are stronger than you think - this is not just easy words, look at the EVIDENCE:
You have insight into how you got here and you know that you are capable of forcing yourself to go out as you did so before.
You are well-educated and articulate.
Deciding to leave and doing it is the single hardest step and you have already done it.
You have firm views and are capable of being assertive.
At the moment, you are at the bottom of the mountain and the top seems impossibly far away, so focus on the steps just in front of you. Only you can decide your own priorities. In your situation, these would be mine:
Marriage - decide if you can ever be satisfied and sane with your husband being openly unfaithful. Can you disengage, find interests, friendships and even romance for yourself? Or will you obsess over his partners, what he's doing, what his girlfriends think about you etc. What impact will it have on your relationship with your sons - would they respect your choice or would they lose respect for you? How secure would you be that your husband might not at some point leave you for a new partner? If you go back, will your husband's behaviour worsen now he knows you will tolerate it? If so, what's your plan for working on yourself and living a separate life under the same roof? How will you protect yourself emotionally?
Getting help to feel more positive and understand that just because you've seen bad things happen before, it doesn't have to be the same
for you.
Children - call them, ask to meet up. Don't talk about their father, ask how they are getting on, what they're up to etc. Ask them to think of something they would enjoy doing one on one (meal out, cinema, pub, walk in the park, whatever) and commit to doing it, just you and them.
Divorce, if that's what you decide. You have to have a solicitor, like it or not. Find a good one, ask only for what you're entitled to (50/50) and there does not need to be a fight.
Sorry for the long post, I just want to help!