Need serious advice
I've been with my fiancé for 4 1/2 years, engaged almost 3 of those. We were supposed to get married January 1st this year but SS18 was sent away because of drug abuse and gave his dad a line of crap that he wanted to be at our wedding so we called it off. (Once he was released from the facility we didn't hear from him and he stole from us so he is not concerned about a relationship with us).
My fiancé often brings up that he wants us to get married and that we need to plan it soon so we can be married soon. I am always very vague when he brings it up because as much as I love him and want to be with him, the whole situation is wearing on me and I don't know if I should commit to marriage, and I don't know how to say that without crushing him. All is well in his world, mine...well he took a job last December that put him on second shift, 3pm to 12:00am. SD19 lives with us and SD11 lives with us and two of my daughters, 19 and 11. SD19 thinks only about herself and runs around with friends all the time. She basically treats the house like the Holiday Inn, here to sleep, eat and shower and sometimes gone for days in between. Doesn't help around the house and just eats and drinks everything and does nothing to contribute. SD11 is bossy and mouthy as hell and I've had to put her in check several times. She and my daughter are in the same grade, same school, same classes, and when it comes to homework all she wants to do is argue with me. Long story short, it just feels like I am a single mom again but only times 2 kids to deal with. I work 8am to 5pm, come home and start dinner, sit them down at the table to finish homework, get them fed, and work on homework until 10:00-11:00 at night all the while arguing with SD11 about her homework. She is supposed to go to her BM's every other week but BM "doesn't have room" for her to stay with her and her boyfriend at her boyfriend's parent's house (yes they are both around 40 years old living with his parents). Here nor there, I'm here raising their daughter making sure it all gets done. It was 11:00 tonight before I finished dishes and hadn't eaten or changed out of my work clothes. I am wearing down. I'm a patient person, and kind-hearted and feel like a bad person for how I feel about the situation. I resent the SDs and don't want them here. Getting married locks me in to how many more years of this? I love being with my fiancé, when we don't have kids around it is amazing. I just don't know how to say I don't want to get married because of his kids because I know he's in a tough spot having to work nights and not being able to help. But dang it. And I want him to accept my kids and I know they are not saints or easy at times but they are at least respectful. His girls just need to go live with their mom, they don't see their dad anyway.
How do I even have that conversation with him that marriage just doesn't seem like something I want anymore because of his kids?