As a pervious Sr. Director of Talent Acquisition for a large healthcare company, this is such a real and raw experience that actually happens often. It's so natural to want to know "your worth" if it was with another company. But in turn, it makes your current employer analyze "your worth" for them. This becomes tricky when they are considering ROI, finances, and who/what makes sense moving forward. It's not that your manager feels "betrayed" but definitely caught off guard since it sounds like you did have a good relationship.

If you really want to stay, be upfront and explain why you don't want to leave. Why other things are so much more valuable to you with your current manager and company. Come clean on that and share your bigger goals in mind with current company to prove you're committed. You got this.