Dolly Firstly I am so sorry to read about what you've been going through. Being left by someone you trust and love is horrendous.
You've had amazing advice on this thread. I went through something very similar 7 years ago and wish I'd posted on MN at the time. Perhaps if I had I wouldn't have taken the scenic route back to recovery....! I went via denial, delusional hope, regret, begging him to come back, sort of getting him back for him to leave again, bitterness, depression and so on. I would have done anything to patch my little family back together and protect my DS.
The advice you've been given is spot on and I hope minimises some of the pain for you. I don't have anything to add except to say I thought I'd never cope / survive or be happy again. I was left with a 4 month old baby and found out my ExP had essentially been with someone else for 2 years too. I felt incredibly vulnerable because I felt like I'd been living with, and had a baby with, a stranger.
Like you I also got texts which were very "pity me" - what I learnt the hard way is that he just could not be trusted. His promises, his guilt, his love - nothing could be relied upon.
Anyway - I came on board to let you know that the pain does pass - and that you and your DCs will be fine. Though you may not feel like it yet you are in a much better situation than you were 6 months ago when you thought he was reliable and your DH. You're already stronger than you realise and this chaos will die down and you'll feel in control of you life again.
Hold your head up high, keep doing the right thing, remain dignified and surround yourself with friends / family who love you and you can trust.
If I could go back and say anything to myself 7 years ago it would be "he's not worth your tears or your pain - and there's much out there for you...." ! No one has the right to lie and deceive someone and you're worth much more than that.
FWIW I wound never want to go through the same thing again - however I'm able now to be grateful for what it taught me about relationships, lying, love, friendship, family, being a mum, money, work - the list goes on. It was a crash course in all that's important.
Good luck. You have nothing to be nervous about- you're doing amazingly.