I think feel disappointed makes a lot of sense, but as we both know, the pregnancy will come either way. You do have an option of giving your child to an adoptive family, but I don't get the feeling that you're at that stage.

The issues with the guy and his mom seem like they're a bit of a mystery to me. What exactly is she saying to him? Why does she want him down? Do they both appreciate that you need help right now? I think this is a good time to talk to your boyfriend and clarify what they've been talking about and try and explain to him, calmly, that YOU need him there more than his mother does. Just be rational about it. If it makes sense, he will be convinced. You need to impress upon him the reality of the situation, the role you would like him to play, and invite him (rather than order him) to acknowledge his duties to you and to his baby, even if it means not spending time with his mom. You can offer some alternatives for him, like talking on the phone, emailing, etc.

I'd also recommend you try not to turn the mother into a villain. From what you described, it sounds like she's needy, but not mean-spirited. She might also be a little absent-minded and unrealistic. If you can find a way to deal with her, even befriend her on some level, you might be able to find solutions that keep everyone happy -- solutions that don't require your boyfriend to have to choose between pleasing his mother and girlfriend. Befriending the mom, even just casually, might also make her back off your relationship.

Best,
Edahn