trips, tears, and trouble

I have a very close relationship with my step-dad, but not in a pedo way. I'm going on a Beta Club trip to Lafayette tomorrow, and I live in Baton Rouge. I've never gone anywhere without him, and he's made up the absence of my abusive father for a few years now. Im staying in Lafayette for 3 days: Wednesday, Thursday, and Friday for the convention. Around 8, we went to bed and my stepdad came and tucked me in bed (I am 13). I started crying because I was going to miss him a lot. He's my protection, my human anti-depressant. He works at Kenan Advantage, so usually he wakes up around 2 in the morning. He cared enough about me, he stayed with me for 2 hours calming me down and reassuring me it's going to be okay. He dropped his snot-towel (he's sick), and I went to his room to give it back. I started crying a little And my mom started yelling (yes, at 9pm) at me for being a drama queen, little brat, and other names. I walked out and about 30 minutes later, my stepdad came back. He stayed until 10:30, and told me it'll be alright. 
My biggest fear is losing someone because of someone else. My father is trying to sabotage my mom and stepdad's relationship to get back at him, and it's costing them a lot of money because of lawsuits and other crap. 
Questions, is it okay to cry because it's the last time you'll see someone in real life and won't be back for a while? Is it okay to feel scared and depressed when you're left alone in a room with people you're not comfortable with? Did I really deserve to be yelled at? Does anyone else have this fear as well?