Well done, Natalie, you are doing a lot better than you think. Remember, you have not been dumped by this loser ( Jeez, I nearly fell off my chair when you said he was 40, he sounds like an immature 16 and by now he won't get any better). You have made the decision to leave this waste of space behind. You are going to build a good and wonderful life with your dc. He could add nothing but misery to this. There is no reason for you to contact him at all. If yo absolutely need the money back, ask your dad or someone to deal with it if you can.
You may remember I am a midwife so the following advice is based on a lot of experience: eat what you can, when you can. If you can add in some fruit and veg that's excellent. As others have said, juice, soup, milk, hot chocolate are all easy to get down. Cereal with some fruit, jacket potato with butter? And take a pregnancy vitamin for extra reassurance.
Secondly, under no circumstances have him at your birth. Don't let him even know. He has lost the right to even know and even if you were happily married no man has the 'right' to be there. It is up to you and you need support not stress. You get to say when he meets her and where and for how long.
Thirdly, the PP who suggests not having him on the birth certificate makes a good point. It's up to you. However, as a single mother with full residency you hold most of the cards.
Please stay no contact. He is bound to come crawling sometime and try to wriggle his way back in to your life. To see this coming allows you to plan and protect yourself. It's what cheats and cowards do, learn the script and you are emotionally able to detach and realise what a pathetic specimen he is.
Good luck and stay strong.