Gonna stop breastfeeding a little emotional 😳😳😳😳

Well my son is 4 1/2 months and I think I'm gonna stop breastfeeding soon. I'm sad at the decision but I hate pumping and he's sleeping longer at night so there's been a decrease in my supply. I'm sad because it's an emotional attachment we have arghh. Also I have to go away for training for 3 weeks (him and my bf will be with me but at hotel) so I would have to pump faithfully... Something that I'm not accustomed to at all. Probably pumped maximum 10 times since after giving birth. Well my question for you moms.. What are the steps to stop the milk from coming in? Also I had mastitis before and my left breast feels like it's coming back in a way because I am engorged under my arm and it doesn't fully go down 😕😕😕😕😕😕