I've read the exchange between you & ldjesus about your situation. A couple of aspects of it reminded me of me a decade ago: My ex-husband's life was "over" when he found out about the expectation...that's a major part of why he is now my EX. Second, your X-BF, like my X, started making "I wanna be a daddy now" noises after a new sweetie came into his life (in my case the time lag was years, not months).
The reason I quote this particular post is simple. One thing that jumped out at me about your ex is that he feels he needs control (or maybe it's the gf who needs the control). A little background is in order. My ex didn't bug me much, nor I him, for years after the divorce. The visitation was minimal (one Saturday or Sunday afternoon a month) for 7 years, by his choice. Enter the new woman. She has gone behind my back concerning scheduling/timing of visits, has her calling her "Mom" (a big no-no, according to the divorce decree; my second husband is not, and has never been, "Dad"), and (with my ex) cites ME as an excuse for why things aren't a certain way. Things started getting acrimonious between me & my ex to the point where legal action was threatened if I didn't acquiesce to his/their demands for increased visitation, with me providing the transportation of 100 miles 1-way every other time (the decree stipulates that transportation is his responsibility, unless I were to leave the state). I decided to make the opportunity for increased visitation available; however, this was pretty much met with, by their behavior, "we really don't want to schedule additional time." The only result has been that now I don't know what their intentions are until the last minute; even when a date is scheduled, they have changed it with less than a week to go 2 of the last 4 times. I have discussed this with my ex on several occasions in an effort to get things stabilized, but to no avail; it's actually gotten worse. Our plans are etched in Jello. Also, the CS, which had come like clockwork, evaporated to the point that I had to go to the authorities to garnish his paycheck (now I'm "keeping him from realizing his dreams," which they have also told the child).
My pre-teen daughter is now at an age where she wants to pursue activities, i.e., sports and a social life. My ex and new sweetie want her in their town during visits; I can at least live with that. Hence, the effort to get the schedule stabilized as much as possible so she knows what's coming/where she's going and I know what to schedule when (as far as I can do so) . Unfortunately, he seems to have little regard for what this pre-teen wants to pursue, e.g., she is on the ball crew for a major college volleyball team; although he was expressly invited by me to come, he has not seen her once. This sounds, again, like a control issue (see my earlier post responding to the actual query).
My point (as well as allowing me to vent :-) ) is to concur w/ldjesus on this point: Document, Document, Document!! Try not to have to go to court (but don't let threats buffalo you either; the documentation will be on your side). If the X-BF stays in, I suspect you are in for a rocky road as this child matures. Keep the faith, do your best (none of us is perfect), and the child should turn out OK.