Is my mother being deliberaltely secretive or am I losing the plot.

[SecretsAndStuff21]

In a nutshell:
My mothers long term partners son left his pregnant girlfriend to hook up with a colleague.
Ex girlfriend had baby and DM and partner were supportive; regular visits etc.
I was eager to hear how she was doing and Mother was forthcoming with updates of mom and baby.
My daughter met them a few times and took lots of photos of her little girl.
I was so pleased she was coping well and sent assorted gifts via my mother.
This went on for a year; no feedback from baby's mom, didn't expect any.
About 6 weeks ago I had a massive bargain haul of gorgeous stuff for the baby, I passed it on to DM to give to her when she visited as wasn't suitable for her right now, but too good a bargain to pass on by.Some of the stuff was aged 3, and I asked if she would mind me sending this stuff as it
DM said she had posted it and said nothing more.
I then was told by my DD that this estranged girlfriend had had another baby.
I called my mom ( she never answers the phone now ?? only sends texts)
Mom actually phone to say she had " forgotten" to tell me this fact.
Thing is only a few months ago she mentioned this woman had met a chap and was taking things slowly.
DM is backtracking and telling me things were serious from the start. Am I going mad? Is DM gas lighting or what?

Well family doesn't have to mean blood - ours doesn't - but what strikes me as a bit odd is that you don't seem to be particularly close to this woman, you say your mum visits her every few months but do you actually have much contact with her yourself? If you don't really know her then it is a bit weird to be on the lookout for clothes and spending money on stuff for the baby etc, a small gift for the birth is nice but maybe she doesn't want these bundles from someone she doesn't really know?

With regards to your mums memory I really don't know, it's impossible to guess from what you've said here..