Yes, I think, you are overreacting. If your therapist has been very good with follow ups so far, it seems a bit impulsive to rush to conclusions that she is not a caring person based on the fact that this weekend she didn't contact you. So, to me the word "betrayal" is too strong for this type of s situation. It's ok to feel whatever you are feeling and there is no need to beat yourself up for feeling this way and to think of yourself as immature etc., but it's a good idea to do the reality check first.

If I was in this situation, I would definitely talk to my therapist and tell her that when she broke her routine of contacting me, it affected me and, of course, I would also like to know why she didn't contact me.

I wouldn't, however, characterize what she did as a betrayal until I talked to her.

I also would want to abandon this routine, at least at some point, and to become less dependent on her. I think, it's ok for a therapist to check up on a client in time of crisis, but I don't think it's healthy to make it a standard routine. As a therapist, I would not encourage it.

It also seems more appropriate to me for a therapist to make themselves available for additional contact between sessions when it is needed as opposed to initiating the contact.