Need Advice

I'm in need of some help. My hubby and I have been together for over 6 years and have children together (I'm also currently pregnant). He has a friend that he dated years ago that he speaks to regularly (they're both from Venezuela, but he's here in the USA with me). I should add that she's also married and has never done anything disrespectful towards me or my relationship. Anyway, about a week or so ago she's blowing up his phone. Apparently she has no food in her house and wanted my hubby to send her $300 so she can get food (for anyone who doesn't know it's really bad in Venezuela right now and their citizens are really struggling). He told me that he told her that he couldn't do anything to help as we are just getting out of financial hardships and still not above water. Well, I checked our bank account yesterday because of an email and I see that he wrote a check for the $300 to her, but because the account is in the negatives it couldn't be processed. I'm pissed!!!! Not only did he lie about the whole thing, but here I am struggling to pay bills and he's trying to send money behind my back to his ex!! I flipped out on him and he said that he was sorry, but I can't let this go. He lied to me for over a week about this as we had several conversations about it. Before I went into the account he told me how much it was in the negatives and I asked him why it was so much and he told me that it was from a bunch of fees. Obviously it was from the $300 that was temporarily taken out plus the return fees and other fees from the transaction. When he originally did this I still didn't have all of the rent paid yet, but he still tried sending her the money behind my back. I just feel like he put her above his kids and myself. What would you guys do? I'm barely talking to him right now.