How to not feel bad about leaving job?

I'm 99% certain I will have two good job offers by the end of this week. I've been at my current company for three years. I'm underpaid but the work I do like. In fact, it's my dream job. They've also treated me quite well when I got diagnosed with cancer 3 months into the job, gave me an extra bonus when I was off for a few months for treatment and always stressed that my job would always be here and to focus on my health. I got better and for a year, things were good. The past year though, it's been a rollercoaster of additional health issues. My mental health has taken a toll. I've been communicating when I need time off, always putting in when I am going to the doctors in my calendar (we have a flexible schedule so I don't need to use PTO for this), but admittedly not being super open about what is going on with me. As a result, my work has been lackluster and they are annoyed at my lack of real communication. I got a harsh review but it was fair. I am being placed on a development plan for three months to improve. There is a long list of other things I'm frustrated by and I feel I need a new start. I thought I was going to be fired, so for funsies, I threw my resume out and got a lot of bites very quickly. Quicker than I thought. I feel bad because it leaves some of my coworkers in the lurch, in terms of work load. I'm sure they will hire some vastly underpaid new grad to fill my role. I just feel bad if I just up and leave, especially since I'm giving all the signals that I want to do this plan and stay, and work harder. I'm 35 and this is only the third job I've ever had. I tend to stick around at them. I feel I need a change. Though I'm sad because I also feel like I'll miss out on some really good projects (I work on building facades). Trying not to burn a bridge either but feel like I will if I give my two weeks notice not long after signing and setting up the development plan (and telling them I really want to stay lol). I hate having feelings.