Today I spanked my son for the first time. I’m emotional

My son is 17 months old. I have a month old son as well. First child kept going to 2nd child’s rocker and touching him. Poking him. Pulling him. With varying intensity. I kept telling him over and over no. I looked him I. The eyes and made my point clear. I put him on time out a couple of times. He kept doing it over and over. I want to change the newborn’s diaper and he climbed up the changing table and stuck his finger in his brothers eye. I snapped. I pulled him down and spanked his butt like five times. I feel really bad. I don’t want to make this a habit. I am anti-spanking. My father was anti-spanking but my mom was very pro. Not entirely abusive but enough to make me see the wisdom in NOT spanking your child. I don’t know how to handle this issue. He says words and talks all the time. Just not in words. I don’t know how much verbal communication is really getting thru to him. I don’t want to spank him again. I will be assigning a chair and location for time out. I feel like something has changed between us today. I feel like ...I can’t figure out the word. Betrayal? Crossed the line? I don’t know the word or phrase but it sux. Ladies. I don’t know how to process this. I feel guilty. My Husband is a huge help and definitely does his part but he is away working and can’t come back for another couple of weeks. I have a cousin staying with me temporarily and my Mom lives with us. Today both had the day off. These two kids require three adults. Newborn has to be held day and night due to reflux and head shaping. Toddler is very active and is taken to the park twice a day. Today was a rough day. I’m getting some ice cream.