Ignorance...

Ok, so I work a part-time job as well as a full time job. My full time job takes a lot out of me due to the fact it's shift work and now even more so because of the pregnancy. I love my job, but I wish so much for a straight day job with holdiays and weekends off.
Now it seems as I start this part-time job, that things are going to take much more out of me without my consent. I signed up for this pt job thinking it would only be 1 or 2 days a week. It appears that I was very wrong. This job is also shift work and while I don't mind 12 hours shifts, they happen to also work 24 hr shifts. I got here today and talked with one of the senior full time workers here and it has been brought to my attention (which I had already seen the schedule but obviously didn't notice) that I'm scheduled to work days that are impossible and also scheduled for a shift that I specifically asked not to work which would be 24 hrs. I know that a 24 hr shift would be better because you'd work it and be done, but I physically just can't do it. 12 hrs are hard enough on my body and my mind. I would go crazy sitting here for 24 hrs.
But on top of that, I'm getting more hours here than full time workers and I don't agree with that in the least. I know that the other girls know it's not my fault, but I didn't come here to step on anyones toes and I sure as hell didn't sign up for this crap where the one in charge doesn't listen to his employees about what is best for them. We work the hours and we know whats best for us. Tonight makes my 5th night in a row to work. Why? Because he didn't look at my full time schedule to see what it was...he just looks at the days that say "OFF" on them and makes the schedule. The other day that is impossible is a night shift with me starting my day shifts at the full time job the next morning. Hello? Can't happen. And the 24 hour shift was changed without my knowledge and I wasn't asked if it was something I could do. I mean, how do you change a part timers schedule without even asking them?
And I know that I seem to gripe about it a lot especially to hubby and I know he's probably tired of hearing about it, and I don't want to disappoint him with me quitting especially so soon but I just don't agree with what the boss is doing here and I don't have to work here. I'm doing them a favor by signing up and this is secondary. I don't need this job or the crap they keep trying.
My delimma is that I don't know what to do or say. I don't want to be rude but at the same time, no one is asking me what I can do or what is good for me. I'm working all of this in between trying to spend time with my husband, going to dr appts, working a full time job and trying to have somewhat of a life. I'm tired and stressed and my body aches. I don't need all of this. I don't really want to upset anyone and I know that I shouldnt care but I do...because that's how I am.
And honestly, it doesn't even end there. Not only was it brought to my attention when I started here, but it was brought to my attention again today that I'm the center of a couple of rumors up here. What is it with everyone and their damn rumors. Are you people so damn shallow that you have to start crap with the new girl. Get the eff over it already. I'm happy where I am, I didn't do the things that were said, and I sure as hell don't want to get with a stupid ass fire fighter. SORRY!! Not my cup of tea. Thanks. I am very much in love with my COP!!!!! I am just so aggravated.
And what do I say? How do I go about telling this boss that I can't work the certain days and how I feel about it without being a bitch about it? I've already started a letter but it doesnt seem to matter how I word it, it just sounds rude. And does it even really matter? If I write him with these concerns will it even matter and will anything be done to change it? From what I'm hearing, no it won't. I just hate this and I want to quit so bad. I've never really wanted out of something more than I have this. *SIGH*