How do I update a variable and all subsequent variables once a certain condition is met in R?

Suppose I have a dataframe with timeseries data, and associated values:

I want to assign group nuymbers to the data where the gaps in time are less than 25 minutes. Using ifelse, I can assign groups to rows where the gap in time is less than 25 or greater than 25:

ifelse(df$Gap < 25, 1, 2)

But I would like to assign all subsequent observations the same group number until another gap in time greater than 25 is observed, as is follows:

I tried doing nested ifelse statements, but to no avail:

Group <- 1
ifelse(df$Gap < 25, Group,
      ifelse(df$Gap >= 25, Group+1,
            ifelse(df$Gap[ >= 25,(Group <- Group+1), Group)

Updated to fix a typo.

>Solution :

df$Group <-  cumsum(df[['Gap in Time']] > 25) + 1
df
         Date and Time Value 1 Gap in Time Group
1  2023-02-01 12:00:00       X           5     1
2  2023-02-01 12:05:00       X           5     1
3  2023-02-01 12:10:00       X           5     1
4  2023-02-01 12:15:00       X           5     1
5  2023-02-01 13:00:00       X          45     2
6  2023-02-01 13:05:00       X           5     2
7  2023-02-01 13:10:00       X           5     2
8  2023-02-01 16:00:00       X         175     3
9  2023-02-01 16:05:00       X           5     3
10 2023-02-01 16:10:00       X           5     3