need some reassurance

My son is 7 months and 20lbs. He's been sleeping in his crib since he was 1 month. Anytime he would cry throughout the night, I'd rush to his crib to soothe his needs. I'm transitioning him now to self soothe and when he wakes in the night, I am letting him fall back asleep on his own. This week has been so hard on me and him. I need routine and he does too, but oh my goodness my heart has been hurting every night he wakes and cries for around 30 minutes. I watch him on the monitor just to make sure he's okay. (He's crawling/standing now in his crib). Is anyone else doing this? I know everyone has their own personal beliefs about sleeping methods and crying it out, but my husband and I share a queen bed and he wakes at 3:30am for work...so co sleeping isn't going to work. I just need some reassurance this gets easier. I feel like a bad mom. :(